MTH Dash 8 making gear noise

[enginear joe]

 I ran into my first Dash 8 having a gear box issue. It's a used CP 6 axle engine and I have no idea of it's history. There was plenty of grease in the gearbox yet the very front axle needed some lube at the bushings. Not enough wear to cause the noise. I powered up the engine laying upside down and found the issue. I could grab that very front axle and make it stop. That would yield a large clicking sound while the motor was running. I could not spin that axle and all the gear box screws were tight so I went inside. I could see minor evidence of the wear of the idler slipping while the motor's worm gear spun. If I pressed down on the top of the motor it seemed to be enough to get the gears to mesh. So I created a plastic half-moon shaped shim with a thin flat top that sits on the front motor cover. It gets pressed down when the gear box cover goes on. It's enough that now the axle does not slip anymore.

 I can only guess at what happened. There is big evidence of this engine being worked on by someone. They didn't know enough to disconnect the handrails from the cab. There's all sorts of evidence of that from one having the whole end broke off. Another elongated the cab hole severely. The front grab is missing on one side too. So I don't know when that occurred? Maybe the owner tried going inside for the gearbox noise? Or maybe it happened for some other reason? Maybe the gearbox cover at one time was left loose?

 I also happened to find a brush had broken free from it's wire. That allowed it's spring to contact the axle gear and wore the spring severely enough to cut it. I re-soldered everything back and should replace that whole set-up when I do the next service. The engine overall is in good shape, minus the abusive workmanship. It doesn't show signs of big usage and looks like a newer model PS2 with polarity switch. MTH site shows it's 2005

https://mthtrains.com/70-2025-1

 I'll have to keep an eye on how it runs. I didn't see any special reason why this occurred. I can only think that the box had too much play, or the cover was left loose at some point? So keep the boxes tight and lube the axles!