started falling off. The tender leans to one side. The locomotive wobbles going down flat track. It has no flywheel so it is totally unforgiving of dirty track. Finally, after the mechanical problems were resolved, it started stuttering with getting little or no movement out of it. Polishing the wheels made a significant improvement. All in all, a beautiful engine, but a serious quality disappointment for the price. It helped shape my opinion that I would never buy another Con-Cor engine again. Not really an issue since they are closing up shop soon.