Bit of a fraught morning, or couple of days here at FSQ. The other day, the B12 61533 was bringing in the "GE" train, when it failed completely. After a few seconds, it would move forward about half a turn then stop again. And so it went on, as if the motor was overheating, although the was no heat to be felt. With the help of the Big Hand from the Sky, and an L1 that happened to be in the Loco Spur, the train eventually reached it's terminus, and the B12 was dismantled for inspection.
Nothing visibly amiss, so a dead motor was assumed. None of the usual sources seemed to have any B12 motors in stock, but the motor for the Hornby S15 looked as though it was the same, albeit with a different part number. One was ordered and duly arrived this morning.
The motor is indeed the same. But the flywheels are different! The B12's flywheels incorporate the coupling for the drive shaft, whereas the S15s have a hexagonal recess in the end. Don't know how that works as I haven't got an S15. Anyway thinking nothing ventured nothing gained, I got one of the flywheels off the dead B12 motor with a lot of brute force, a broken scriber as a drift and a big hammer. The diameter of the flywheel was bigger than the motor, so the flywheel could sit on the jaws of the vice. However the S15's flywheels are smaller so all I could do was clamp the flywheel as tightly as possible between the jaws, and keep hitting until the motor fell out of the vice onto the floor. Then repeat, until eventually the flywheel was off. Then pressed the B12 flywheel onto the S15 motor shaft, using a big G Clamp as a press.
After all that mistreatment, luckily the new motor still worked, and was installed in the demic loco. Putting the body on however, it would run backwards but not forwards! Dismantle again (not helped by the almost impossible location of the rear end fixing screw, beneath the cab floor) and found that one of the motor feed wires was getting trapped in the slot in the flywheel! Sorted that (I hope) and re-assemble, then notice the coupling rods are upside down! Initially cursing Hornby QC under my breath, I then realised that I'd put the driving wheels back in back to front when I'd taken it to bits the other day. B12s have an equal driving wheelbase - who knew! Not me, evidently, or I had forgotten. Anyway easily enough swapped round again, and 61533 seems to be a good runner again, in fact possibly better than it was before.
Here are the two flywheels, S15 on the left and B12 on the right (attached to the dead motor).
61533 is now back on shed, waiting to take its back working in the evening. As you can see, apart from the motor it s still in 'ex box' condition. This B12 was used on the M&GN Section, for which it had a tablet catcher on the left hand side of the tender. When the M&GN closed, it spent its last few moths at Cambridge. The tablet catcher was removed but I have a distant photo of it, in "LNER 4-6-0s at Work", which shows that something remained on the tender side, probably the bracket that the tablet catcher had been fixed to. I was hoping to find a better picture to enable me to model whatever it is, before weathering etc, but so far have not ben able to.