I have a fairly new-old-stock Bachmann GP-40 that has a problem with the powered back truck assembly. When I got the unit out of the box for the first time ( I don't remember if I bought it years ago or inherited it from my dad ) it ran for a minute and then it lost drive to the wheels on the back/powered truck. I took it apart and there was a lot of lubrication oil on the entire drive shaft assembly. It took several cleanings until it would stay together; however in the process I think I somehow damaged the assembly as now the front axle of the drive truck is slightly higher than the rear axle and it frequently derails. I tried taking it apart and reassembling it. If I get it loose enough that it sits level, when I stop the engine, the rear axle on the drive truck derails to the right. If I tighten up the assembly to where the truck sits level, it's too stiff to navigate the curves. If I run the engine in reverse, where the powered truck is leading, the engine runs fine. Any idea what I've done wrong and/or can remedy the problem ?
Your first few posts get held up in moderation, but if you stick around that will go away. Regarding your question, it sounds to me like something may not be seated correctly. You said the front axle of the truck is slightly higher than the rear axle, which leads me to beleive that the rear axle may not be correctly seated, which would keep the truck frame from fully snapping into place, but without actually seeing it I can only guess. I do have a Bachmann GP40, but it's been awhile since I've had it opened up, so I'm not 100% sure what the culprit could be. I did find a diagram on Bachmann's website that might be helpful though. https://www.bachmanntrains.com/home-usa/dwg/dwgs/HO_GP40.pdf Here's another one that might help also. https://www.hoseeker.net/assemblyexplosionbachmann/bachmannemdgp40pg02.jpg
You can join the Bachmann HO forum and ask, No waiting. They have a repair center you can can call.
https://www.bachmanntrains.com/home-usa/service.php
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
I did see in the photo you sent me in a PM, the motor is in the center and a worm over the unpowered end. Looks like no gears on that end.
The company name, Google says made model airplanes. Strange.
Someone might have stripped out the gears. Maybe a cracked gear.
Bachmann never did that to my knowledge.
Riich