Ran my BM Mallet few days ago, great fun, ran fine.
Tried again today, and the front truck was frozen and back truck made crunching noise!
So are there two problems suddenly? Or one related problem? Went on the BM site and got the exploded diagrams. Followed the directions to loosen the boiler.
I took off boiler and dropped both trucks (a LOT of stuff in there), the motor is vertical over each truck. Multiple plugs to pull, caution advised.
So I found that the rear truck motor was loose, which accounted for the grinding sound. Further investigation revealed that there are two screws holding the motor to a collar on the top of the truck. They are inserted through the collar and into the motor casing from below (the truck side) Both missing! That is clearly the problem, no sign of the screws in the truck, where they would have fallen, but the truck is open on one end, so they are gone, Somehow need to find them somewhere, starting with BM I suppose.
A poster on the Bachman forum had the same problem several years ago but apparently did not lose the screws- they may be #10613 but very hard to tell from the exploded diagram.
The front truck motor is secured properly, not sure why it was not operating, That issue is yet to be dealt with.
This is a continuing saga, stay tuned.
I will post on the forums and see what I come up with, never bored with large scale trains as a hobby.