Despite my best intentions to put the troublesome Dean Goods project aside for a bit, I couldn't resist taking it out again for another session of tweaking. If you've been following the complicated saga, the latest thrilling twist was that the new gearbox seemed to be wearing out a bit prematurely - ie, over one weekend. Eek!

In the comments on the earlier thread:

http://www.rmweb.co.uk/community/index.php?/blog/257/entry-15636-dean-goods-the-saga-continues/

it was suggested that the gear meshing could be improved by elongating the motor mounting holes a touch, and that I should also file a flat onto the driving axle to alleviate any off-center effect on the main gear. As it was, I had filed a flat but maybe not enough of one, so I stripped the model again and filed a more pronounced flat onto the centre axle, taking care to ensure it was wide enough to pick up the grub screw. I also elongated the motor mounting holes a tiny bit. Because of the wear on the main gear from the second gearbox, I substituted the original gear, which to my eye was not as affected.

Loco reassembled. Back on the track. No real improvement. It moves, but there's clearly a lot of mechanical resistance when the gears are engaged. With the drive gear loosened, the chassis is as sweet as a nut, so that's not the issue.

Loco stripped down again. Elongate the holes a bit more. Reassemble. Back on the track. Better, but still not fantastic. But heading in the right direction?

Right. Back on the bench. Strip down. Elongate the holes yet again - but only a tight bit. Ream out the gear box bearings just a tiny, tiny bit. Then back together. Thank goodness for Markits and self-quartering wheels!

Right - progress. There's no cyclical gear noise, now, just a steady hum, which makes me think that the axle flat must be working - and the running is dead smooth at all speeds, and starts on speed step 1. On the other hand, it gets up to a decent plod at speed step 28, so the mechanical resistance must be less than before.

Dare I solder the brake rods back on and hope for the best?