I had my Diesel model since the beginning of July. No, I was not roughly playing with him, and my track is clean.

My Bachmann Diesel was randomly quickly stopping at times, so I thought I'd take off the part of the underside that holds the wheels. I was just trying to clean the wheels, then I screwed it back on, and seemed to move worse. He just totally stopped at random times. Then I tried to fix it again, but one of the copper things behind one of the wheels broke off, and now he doesn't move at all. I guess there's no way to get him fixed. I'll just have to spend my money on ANOTHER model.