My Hornby Networker came to me rather broken. I fixed it up with some needed spare parts, but it never really worked properly, needing continual assistance to get to the other end of my workbench, let alone running on an actual layout.

I gather that's not unique to mine -- they have a reputation. Mine might be a particularly bad example, or it might be typical. The entire unit is a high-friction mess, with every single axle having both pickups and a bad quality sleeve bearing on the axle. Then the drive itself is some awful open frame motor driving a single axle.

I was originally planning to re-work this using Black Beetle components. It made a lot of sense back when I was living in Australia. Now you can't get them any more -- nor apparently any of their competitors.

So ... I found an alternative solution in the form of the Hornby Javelin, which matches the wheelbase and diameter close enough, and for which spares are readily available from the usual suspects. (Although I found buying entire bogies cheaper than axles for some reason. YMMV).

I started by looking at the first problem (rolling resistance) first.

Careful application of a 3mm drill bit to the sideframes allowed Javelin trailing axles to fit into the Networker bogie sideframes. This gives a better wheel profile running in a reasonable approximation of pinpoint bearings:

No, your DCC Concepts Axle Reamer won't help you -- the Javelin axles are shorter than the normal length, and the centre of the bogie kinda gets in the way of the DCC Concepts tools, too. You'd need to cut the centre of the bogie away to get the tool in, and yet that part is both structural and also vital in terms of holding the bogie into the chassis.

If you want to re-fit the weight in the centre of the bogie (I haven't done this yet) you'll need to clearance the axle slot -- otherwise you reproduce the same problem.

My trailing car now rolls reasonably freely. Not great (my precision drilling isn't perfect), but a hell of a lot better than it was before.

The Javelin motor bogie will also fit. It's a bit taller, so the cosmetic seating would need modification above it, but it should still sit just below the windowline, not intruding into the body too badly. The main question is how to retain it in the chassis.

Option A would be to clearance the inside of the chassis to allow easier rotation, and construct something to use the original javelin pivot (on top of the motor bogie). Option B would be to transfer all the relevant clips and supports from the original bogie frame to the new one. I haven't decided which option I should look at yet. I do have plenty of spare sideframes should I end up ruining one or two in testing this out...