N Dapol Class 22 burning smell - Hattons Project #3

[n9]

I'm inspecting the third of my second hand locos recently bought from Hattons, and I'm getting pretty peeved at the evident lack of quality control before putting these things up for sale at close to retail.

 

All three have problems (the first is the Class 40 I've posted about here; and the second is a Dapol Class 52 that just won't stay on the rails through pointwork and which I may post about later.)

 

Anyway, I put the 22 on my DC test oval. I needed to crank it to about 3 quarters power before I got a reasonable speed up (could have been due to decoder settings) but about 1 minute into its run there was a burning smell. I powered it off immediately.

 

I've today opened it up, and this is what I've found so far:

 

 

Can anyone identify what all that residue is on the underside of the main PCB?

 

Also, it surprised me that there was no insulation at all between the underside of that main PCB and the metal body, so as far as I can gather, only the jumble of wires running under it was preventing any contact with the metal body. And those wires don't seem to be soldered particularly neatly to the board, so to my untrained eye it seems a miracle nothing has blown up sooner.

 

I can see some melting too on one of the transistor housings on that main PCB, so my guess is it got hot because of the residue and started melting one of the wire casings, hence the burning smell?

 

Also I'm not sure if that red wire should be making contact with the metal chassis where I've labelled. Maybe it should, I haven't dissected that part yet.

 

This is the other side, which seems to look okay and is a better reference for how the PCB was sitting atop the wires:

 

 

So what do you guys see? Is it fixable or should it be a straight return?

 

 

[Paul H Vigor]

With any model bought secondhand, I always ask myself why is it secondhand? Because someone had a legitimate reason for selling it on? Or beacuse there was something wrong with it? Before the lockdowns curtailed model railway shows, I had a golden rule that any secondhand loco I bought had to be seen running. Covid-related online buying has resulted in so much more buying on trust - trusting the seller to be truthful when describing a model. Most are, others less so. Some are actually decietful, whilst others may just be ignorant of model railways. I like buying secondhand, but we should have a level playing field.

[n9]

1 hour ago, Paul H Vigor said:

With any model bought secondhand, I always ask myself why is it secondhand? Because someone had a legitimate reason for selling it on? Or beacuse there was something wrong with it? Before the lockdowns curtailed model railway shows, I had a golden rule that any secondhand loco I bought had to be seen running. Covid-related online buying has resulted in so much more buying on trust - trusting the seller to be truthful when describing a model. Most are, others less so. Some are actually decietful, whilst others may just be ignorant of model railways. I like buying secondhand, but we should have a level playing field.

Indeed. Although seeing British outline stuff running gets a bit challenging when not living over there. Regardless, if I shop at what I think is still a well known and reputable retailer, and I'm asked to pay close to full whack, the last thing I expect to get is the kind of eBay experience where you wish you hadn't; as it stands I've bought 3 projects, not 3 second hand locos as they were described to me - none of these faults were listed. But I think we're digressing a bit from the main thrust of the post, which is how to fix this loco.

Edited December 16, 2023 by n9
typo

[Paul H Vigor]

36 minutes ago, n9 said:

Indeed. Although seeing British outline stuff running gets a bit challenging when not living over there. Regardless, if I shop at what I think is still a well known and reputable retailer, and I'm asked to pay close to full whack, the last thing I expect to get is the kind of eBay experience where you wish you hadn't; as it stands I've bought 3 projects, not 3 second hand locos as they were described to me - none of these faults were listed. But I think we're digressing a bit from the main thrust of the post, which is how to fix this loco.

Indeed. You/we should be able to buy models with confidence. Hope you manage to fix it.

[Grimly Feendish]

I suspect the coating on the PCB is a protective varnish of some description, put on by the manufacturer. The temperature from a hot wire is very unlikely to melt the semiconductor case. The indent is probably only in the pcb coating.

 

HTH,

 

John.

[Izzy]

3 hours ago, n9 said:

I'm inspecting the third of my second hand locos recently bought from Hattons, and I'm getting pretty peeved at the evident lack of quality control before putting these things up for sale at close to retail.

 

All three have problems (the first is the Class 40 I've posted about here; and the second is a Dapol Class 52 that just won't stay on the rails through pointwork and which I may post about later.)

 

Anyway, I put the 22 on my DC test oval. I needed to crank it to about 3 quarters power before I got a reasonable speed up (could have been due to decoder settings) but about 1 minute into its run there was a burning smell. I powered it off immediately.

 

I've today opened it up, and this is what I've found so far:

 

 

Can anyone identify what all that residue is on the underside of the main PCB?

 

Also, it surprised me that there was no insulation at all between the underside of that main PCB and the metal body, so as far as I can gather, only the jumble of wires running under it was preventing any contact with the metal body. And those wires don't seem to be soldered particularly neatly to the board, so to my untrained eye it seems a miracle nothing has blown up sooner.

 

I can see some melting too on one of the transistor housings on that main PCB, so my guess is it got hot because of the residue and started melting one of the wire casings, hence the burning smell?

 

Also I'm not sure if that red wire should be making contact with the metal chassis where I've labelled. Maybe it should, I haven't dissected that part yet.

 

This is the other side, which seems to look okay and is a better reference for how the PCB was sitting atop the wires:

 

 

So what do you guys see? Is it fixable or should it be a straight return?

 

 

 

In my limited experience of Dapol N gauge stuff this is what you get whether new or secondhand. Not the same finesse of design/construction with regard to electrical parts, wiring/pcb's etc. as you get with Bachmann Farish.  Nothing that can't be fixed though.

 

I get the impression it came decoder fitted? If you can I would fit a blanking plug - if you have one - while sorting it out. Getting it running properly before adding in the decoder.

 

No, I don't believe the red wire should be touching the chassis. I believe this is one of the motor feeds. If it is this may be where the problem was. One side of full power DC/DCC going both to the motor and backwards to the pcb and decoder motor outputs. Hope it hasn't cooked the decoder if one was fitted. 

 

But the basic pcb with the 6-pin socket should be fine just resting on the wires although for belt and braces you could put some insulation tape of some description on the chassis underneath where it sits. I'd also make sure the wires soldered onto the pcb are isolated from each other as well. As you say the actual assembly looks pretty poor, lots of exposed bare wire rather than neat soldering onto it.

 

Bob

 

 

 

 

 

 

[n9]

2 hours ago, Grimly Feendish said:

I suspect the coating on the PCB is a protective varnish of some description, put on by the manufacturer. The temperature from a hot wire is very unlikely to melt the semiconductor case. The indent is probably only in the pcb coating.

 

HTH,

 

John.

If by the protective coating you mean the usual sheen on a PCB, that's not it. There is definitely something else on it - a build-up of some kind that's hardened. For want of a better description, it's a bit like tartar. But maybe that's what you mean?

 

I've only taken apart a handful of locos so far, but I haven't seen what's on this PCB before.

2 hours ago, Izzy said:

 

In my limited experience of Dapol N gauge stuff this is what you get whether new or secondhand. Not the same finesse of design/construction with regard to electrical parts, wiring/pcb's etc. as you get with Bachmann Farish.  Nothing that can't be fixed though.

 

I get the impression it came decoder fitted? If you can I would fit a blanking plug - if you have one - while sorting it out. Getting it running properly before adding in the decoder.

 

No, I don't believe the red wire should be touching the chassis. I believe this is one of the motor feeds. If it is this may be where the problem was. One side of full power DC/DCC going both to the motor and backwards to the pcb and decoder motor outputs. Hope it hasn't cooked the decoder if one was fitted. 

 

But the basic pcb with the 6-pin socket should be fine just resting on the wires although for belt and braces you could put some insulation tape of some description on the chassis underneath where it sits. I'd also make sure the wires soldered onto the pcb are isolated from each other as well. As you say the actual assembly looks pretty poor, lots of exposed bare wire rather than neat soldering onto it.

 

Bob

 

 

 

 

 

 

 

This is extremely helpful. Thank you. It did come with a decoder and I will definitely be fitting the blanking plug when I next power it up. I'll double check that red lead because it looks like it might be touching. I see no obvious damage to the decoder. Probably will put some kapton where things look scary.

 

Having cleaned that transistor, it's casing isn't partially melted after all, so I'm still left without conclusive signs of what burnt to give off the smell.

 

More digging to do...

 

Before I forget, I should be fair to Hattons and say they did offer some discounts almost right away. I'm seeing how bad the damage is on all 3 locos before agreeing to that or arguing my case further. But generally I've found their customer service pretty good so far.

[Steven B]

Ah, a PCB from Dapol's "could do better" phase...

 

The residue on the PCB is probably flux from the soldering - it's probably "no clean" which means it should do no long term damage. It won't be the cause of the problems. It should clean off with some IPA or methylated spirit on a cotton bud/Q-Tip if needed.

 

The PCB should be screwed to the chassis block with two screws. It looks like only one is still there.

 

I'm not sure if the black coating (paint?) is conductive - adding a sliver of insulating tape under the PCB won't hurt.

 

You'd need to check what the red wire is connected to. Is there a matching black one on the other side? It looks like Dapol have used standard DCC colours for the wiring (red & black = track, orange & Grey = motor, yellow & white = F0f & F0r).

 

I'm not sure the component with the burn mark is a transistor - Dapol used twin diodes in the same package. A few years ago they appear to have had a batch that burnt out. I've had issues with them on other Dapol models, mainly HST and classes 26 and 58. The usual diagnosis from what I remember is if the model works normally with the body (and hence lights) not fitted. 

 

With nothing plugged into the decoder socket, check that there's no contact between the motor feeds and the chassis. I'd put some kapton tape under the PCB just to be on the safe side. The wires soldered to the PCB aren't pretty and do have quite a bit of bare metal exposed on the wire. As belt-and-braces, either re-solder them with less exposed metal or paint them to be on the safe side.

 

As suggested, I'd do any further testing on DC, and when 100% happy test on a DCC programming track. Much less chance of magic smoke being released!

 

Steven B

[jpendle]

Where did the decoder get to?

 

John P

[n9]

59 minutes ago, jpendle said:

Where did the decoder get to?

 

John P

It's here:

[n9]

5 hours ago, Steven B said:

Ah, a PCB from Dapol's "could do better" phase...

 

The residue on the PCB is probably flux from the soldering - it's probably "no clean" which means it should do no long term damage. It won't be the cause of the problems. It should clean off with some IPA or methylated spirit on a cotton bud/Q-Tip if needed.

 

The PCB should be screwed to the chassis block with two screws. It looks like only one is still there.

 

I'm not sure if the black coating (paint?) is conductive - adding a sliver of insulating tape under the PCB won't hurt.

 

You'd need to check what the red wire is connected to. Is there a matching black one on the other side? It looks like Dapol have used standard DCC colours for the wiring (red & black = track, orange & Grey = motor, yellow & white = F0f & F0r).

 

I'm not sure the component with the burn mark is a transistor - Dapol used twin diodes in the same package. A few years ago they appear to have had a batch that burnt out. I've had issues with them on other Dapol models, mainly HST and classes 26 and 58. The usual diagnosis from what I remember is if the model works normally with the body (and hence lights) not fitted. 

 

With nothing plugged into the decoder socket, check that there's no contact between the motor feeds and the chassis. I'd put some kapton tape under the PCB just to be on the safe side. The wires soldered to the PCB aren't pretty and do have quite a bit of bare metal exposed on the wire. As belt-and-braces, either re-solder them with less exposed metal or paint them to be on the safe side.

 

As suggested, I'd do any further testing on DC, and when 100% happy test on a DCC programming track. Much less chance of magic smoke being released!

 

Steven B

Brilliant! Thank you Steven!

 

I'd already cleaned the board with IPA last night, mainly because the build-up looked very excessive. There are 2 screws holding the PCB - I just took the picture after removing one of them. And you're right, I've just tested it and the black coating is not conductive. I quite wrongly assumed it was. There is a matching black wire on the other side. There seems to be no continuity with the chassis for either wire.

 

I've just put the loco on my rolling road with the blanking plug in, and there is still a burning smell. I have no idea what to check next. Although I did notice the red light at the wrong end of the direction of travel flicker on and off ever so slightly.

 

Anyone have any further suggestions?

 

 

 

[Izzy]

12 minutes ago, n9 said:

There is a matching black wire on the other side. There seems to be no continuity with the chassis for either wire.

 

Studying the photo you posted I took it both these wires go to the motor terminals. The grey/orange motor control wires from the pcb go to what seems to be a small capacitor sitting on top and I guessed it was just how they had chosen to do the wiring. 

 

Since there isn't much involved, just the pcb to enable a 6-pin decoder along with a few bits for directional lights I would suspect the pcb is faulty somehow, a short-circuit or duff part. Given the quality of the wiring two of the wires touching would be easy I think.

 

Purely personally, since with the prototype the lights were very dim and hardly seen in daylight I don't bother with them, so I rip all the gubbins out and just hard wire a decoder in.  And you can also remove the capacitor since it isn't needed under DCC. With just four wires there isn't much to go wrong ! If you want to keep the option of changing decoders you can always use a 6-pin wiring harness.

 

Bob

[n9]

24 minutes ago, Izzy said:

 

Studying the photo you posted I took it both these wires go to the motor terminals. The grey/orange motor control wires from the pcb go to what seems to be a small capacitor sitting on top and I guessed it was just how they had chosen to do the wiring. 

 

Since there isn't much involved, just the pcb to enable a 6-pin decoder along with a few bits for directional lights I would suspect the pcb is faulty somehow, a short-circuit or duff part. Given the quality of the wiring two of the wires touching would be easy I think.

 

Purely personally, since with the prototype the lights were very dim and hardly seen in daylight I don't bother with them, so I rip all the gubbins out and just hard wire a decoder in.  And you can also remove the capacitor since it isn't needed under DCC. With just four wires there isn't much to go wrong ! If you want to keep the option of changing decoders you can always use a 6-pin wiring harness.

 

Bob

Thank you, Bob!

 

Alright, I think I'll start by redoing the wiring since it's obviously pretty poor. And maybe follow that up by stripping down to the motor.

 

The motor hasn't been mentioned yet. Could foreign objects be burning up in there???

 

I say this because in addition to huge dollops of grease that I found in the bogies, it was a bit like an episode of CSI: I found there what looked like static grass and something that looks like small pieces of gold leaf... Perhaps some of that has worked its way into where it shouldn't?

 

This pic shows the excess grease I removed (left) along with a couple of flecks of that "gold leaf" (a bit further to the right) - I've no idea what that is. I should say that all this aside, the loco looks in pretty good condition.

 

[Steven B]

Is the burning smell there with the body/lighting fitted/connected? Is it an electrical burning smell, or more plasticky?

 

I'd be tempted to unscrew the PCB and with the loco running touch each component to see which is getting hot enough to make the burning smell. The other option is to turn the power up to 11 and see what goes pop!

 

 

Steven B

[Robert Shrives]

Hi , 

Early 22s had what look to be  hand soldered PCBs on a really bad day, the gloop I always thought was a contact glue used to make a "mechanical connection for the wires and "after the event" insulation for the cats cradle of wiring.   

The flickering tail lamp could indicate one of the control diodes on the board is about to go pop. 

 

The motors are quite good and failures happen but not common  in the picture of how many Dapol have used/ use today. - Current consumption is a good check on motor life and at worst might be source of smell but they get hot quick and the black tape in second pic shows no distress.  On later models I have seen a smidge of heat shrink sleeving on the motor joint - preventing your fear of short on the wire to motor/chassis point.    

 

Grease gloop is a pain as a  does dry out and cause drag and easily cleaned off - certainly a case where less is more!   I got a non runner class 150  sprinter off ebay and 15 minutes cleaning out a static grass and grease soup out of the bogie the unit was cured.  It is hard for manufacturers as a scale model ex warehouse is let out in to the wild and treatment not always humane!  yet as it is branded with their name they are to "blame."  

 

Ebay purchases are always a risk but for me part of the fun of the chase- sadly prices no longer the basement bargains we remember - or want to  perhaps! 

 

Viz the 52 did it come with the second bogie in the box - worth swapping if it did and see if running improves - the first batch had some wonky wheels and some with a horrible tarnish on the treads- I hate to think what the builders were breathing if the air made the metal crud up so quickly.    

Robert 

[n9]

1 hour ago, Steven B said:

Is the burning smell there with the body/lighting fitted/connected? Is it an electrical burning smell, or more plasticky?

 

I'd be tempted to unscrew the PCB and with the loco running touch each component to see which is getting hot enough to make the burning smell. The other option is to turn the power up to 11 and see what goes pop!

 

 

Steven B

The smell is electrical, like the Scalextric cars I used to have as a kid, but noticeably stronger than with all the other locos I have.

 

I've had it on my rolling road with the body off but lighting connected (since it's soldered) and I already resoldered all of the wires (I've assumed the wires themselves are okay.)

 

Luckily I have another 22 to compare it with. Compared to that one, it doesn't run as smoothly, but not too bad. They both take around 60 on my Gaugemaster Combi to attain the sort of speed I'd want to have them for running in, but this one doesn't maintain constant speed, slowing quite noticeably from time to time, and then speeding back up again. (This is all with the blanking plug fitted.) The other 22 does this a little, but a lot less. Probably differences in back to backs and wheel alignment come into play there, but I have swapped the bogies out, and while it's then more consistent at running, it still has the strong Scalextric smell. So I think that rules out friction somewhere in the gears and bogies over stressing the motor. The motor just seems to struggle more. I've also measured the temperature at the top of the metal body right above the motor after 10 minutes running, and it reached 40C/104F. I don't know if that's "normal", but it seems quite high to me considering its the outside edge of a pretty thick metal body.

 

So I'm leaning more towards excessive friction somewhere between motor and worms, unless something else can explain what I'm seeing?

 

9 minutes ago, Robert Shrives said:

Hi , 

Early 22s had what look to be  hand soldered PCBs on a really bad day, the gloop I always thought was a contact glue used to make a "mechanical connection for the wires and "after the event" insulation for the cats cradle of wiring.   

The flickering tail lamp could indicate one of the control diodes on the board is about to go pop. 

 

The motors are quite good and failures happen but not common  in the picture of how many Dapol have used/ use today. - Current consumption is a good check on motor life and at worst might be source of smell but they get hot quick and the black tape in second pic shows no distress.  On later models I have seen a smidge of heat shrink sleeving on the motor joint - preventing your fear of short on the wire to motor/chassis point.    

 

Grease gloop is a pain as a  does dry out and cause drag and easily cleaned off - certainly a case where less is more!   I got a non runner class 150  sprinter off ebay and 15 minutes cleaning out a static grass and grease soup out of the bogie the unit was cured.  It is hard for manufacturers as a scale model ex warehouse is let out in to the wild and treatment not always humane!  yet as it is branded with their name they are to "blame."  

 

Ebay purchases are always a risk but for me part of the fun of the chase- sadly prices no longer the basement bargains we remember - or want to  perhaps! 

 

Viz the 52 did it come with the second bogie in the box - worth swapping if it did and see if running improves - the first batch had some wonky wheels and some with a horrible tarnish on the treads- I hate to think what the builders were breathing if the air made the metal crud up so quickly.    

Robert 

Interestingly, the lamp flickering continued for a few minutes after I resoldered the wires, and then just disappeared. Hasn't reocurred, at least not during the numerous tests I've been doing since yesterday.

 

Not sure if this is one of the "older" models you mention, but it's this one from 2013:

 

https://www.hattons.co.uk/59017/dapol_2d_012_004d_class_22_diesel_locomotive_d6313_in_br_green_with_small_yellow_panels_dcc_fitted/stockdetail

 

If I'd purchased this from eBay, I'd have no complaint. But the way this loco performs was not as described by Hattons, and they refused my request twice to test all 3 of the locos before shipping them to me.

 

The 52 I think I will post about, but the axles all look out of whack, and the design of them, if it's the same as the HO/OO version, is not going to mean a straightforward solution judging from the posts I've read - one of them requiring a lathe in addition to considerable modifications.

[Robert Shrives]

Hi It really sounds like the motor is root cause, if you have swapped bogies and much the same - there is not much left. 

class 22 Spare motors might be an issue looking at DCC supplies and Peters spares. Whilst motor is the same flywheels are smaller and so using another motor and trying to swap flywheels might be possible. 

Please drop me a pm . 

 

Robert    

Edited December 19, 2023 by Robert Shrives
add

[n9]

6 hours ago, Robert Shrives said:

Hi It really sounds like the motor is root cause, if you have swapped bogies and much the same - there is not much left. 

class 22 Spare motors might be an issue looking at DCC supplies and Peters spares. Whilst motor is the same flywheels are smaller and so using another motor and trying to swap flywheels might be possible. 

Please drop me a pm . 

 

Robert    

Actually, after my latest tests, I may have found the problem, mainly thanks to the rolling road and being able to poke things as the loco is running. It goes back to the very first pic I posted:

 

 

Something is up with both that red wire leading down to the motor, and the corresponding black wire that does the same on the other side, because when I poked it at the point where it connects to the motor, the flickering lights returned. And after a few pokes to confirm the flicker, I noticed the burning smell... So it seems like those wires must be shorting. When I redid the soldering, I did all the connections to the main PCB and to both light boards, but I didn't touch those. I'll resume tomorrow. But I really hope this is finally it!! Will post an update.

[Harlequin]

Could it be the wire itself that is getting hot? If some of the strands have been damaged, all the current to the motor might be passing through just one tiny strand and that strand could be acting as a heating element.

 

Edited December 20, 2023 by Harlequin

[n9]

As promised, just to round off the story, this is how it ends...

 

🙂

 

The connections to the motor were dodgy. The pic probably shows how bare wire could easily come into contact with the metal body. Painted or not, shorting was happening with the body because just pushing on that area with the loco running caused flickering lights and the burning smell. Perhaps telling, are the remnants of electrical tape that used to isolate the area. (In the pic, it's what's hanging to the right of the motor screw terminal with a tear in it.) Resoldering those wires was much harder than first appeared. I wanted to remove the terminal screws holding the little plates onto which the wire is soldered to reduce the risk of melting anything. But those screws are just carp. They may even have had their heads filled with glue. In the end, I couldn't remove them, and went in with the soldering iron managing not to melt anything. I think you're supposed to be able to rotate those metal plates to keep the solder joint away from the metal body, but since the screws were stuck, I just soldered to the bottom of the plate instead.

 

 

Anyway, that fixed the flickering lights, it cured the burning smell, and I was hoping that would have been it.

 

Sadly, and as suggested earlier, the motor is definitely rogered too. I basically had the motor out on its own with my controller connected directly to its power feeds. It doesn't run at a steady speed. It will for maybe a minute, then slow down, then speed up, all quite random.

 

What I hadn't noticed either until now (because I hadn't dared run it on a track until I knew what the burning was), is that with the body on the thing sounds like a lawnmower. That's as well as being quite wobbly on account of the cups on one axle being worn out or too big. (Yes, I had the bogies and gears apart too.)

 

So that's it really. Sadly I think I'm left with no option than to send this one back to Hattons. From what someone else said, motors for these aren't too easy to come by.

 

I'm left with mixed feelings really. Elated at the amount of work I put it in and at how much I managed to solve, but deflated that in the end it wasn't enough and I don't have a loco that I really wanted. Miffed too, that Hattons sold this to me as "Fine when last run."

 

I've learnt a tremendous amount though. Special mentions to @Steven B, @Robert Shrives, and @Izzy. Your help was fantastic. And thanks to everyone else who chimed in too. Really appreciate it!

 

Here's how she looked after my efforts:

 

[woodenhead]

That's sad I've had two of these little engines and they are lovely runners normally.

[Robert Shrives]

Hi 

please PM me about bogies I might have enough bits to help, as noted they are normally lovely motors. 

FWIW the screw in the bush holds the spring for the motor brush  the brass bush is a force fitted item that is knurled and will not move but if you have tried it is now likely the brush and spring now out of alinement, giving a rough runner as brush will be arching on the commutator, guess how I know this !!

Robert    

 

 

   

[n9]

On 21/12/2023 at 22:12, Robert Shrives said:

Hi 

please PM me about bogies I might have enough bits to help, as noted they are normally lovely motors. 

FWIW the screw in the bush holds the spring for the motor brush  the brass bush is a force fitted item that is knurled and will not move but if you have tried it is now likely the brush and spring now out of alinement, giving a rough runner as brush will be arching on the commutator, guess how I know this !!

Robert    

 

 

   

Thank you Robert! I've turned my attention to some much-delayed trackwork for a few days, but I will be in touch! Very kind of you. I'll likely have another go with the motor itself beacuse from what you say I've probably made a problem worse trying to tweak that screw. I should have at least tried to take the motor apart when I was in there. Those things still largely look like Scalextric motors from 50 years ago, so the territory hopefully won't be too unfamiliar to me.

 

Here's a pic of a bogie. Struggling for terminology, but in those metal parts running along either side, it looked like the indentations that take the pointy-ends of one of the axles were too deep or worn out. Certainly that one axle had substantially greater lateral play than all of the others. Other than replacing those metal parts, not sure if there's another fix?

 

 

 

Bonus question: That back-to-back gauge is hopeless for anything with cogs in it. Is there another design?

[woodenhead]

3 hours ago, n9 said:

Bonus question: That back-to-back gauge is hopeless for anything with cogs in it. Is there another design?

Interaction between my back-to-back gauge and some Dapol Collett coaches did not end well with a couple of wheel failures later - i.e. solved the b2b problem and then some time later (months even) some individual wheels disintegrated whilst running.

 

Been wary of using it since, though I'm not seeing any issues requiring it's use.