A couple of weeks ago I took my MTH French 241A locomotive and Orient Express cars to the toy train museum to run them at open house. This is an engine with several hours of running time on it and no history of problems of any kind. Everything on the track, ready to go, engine turned on, sound working. Crack the throttle and the train moves a fraction of an inch and stops dead. Acts just like it's picked up some ballast in the mechanism. Fiddle with it, fiddle with it - no luck. Pack everything up, ready to start selling my trains and rip out the layout. That is a real "pride and joy" engine for me and I was demoralized and depressed over a very public and spectacular failure.
So, I get it home and pull the boiler. First thing that hits me is that the tach reader is loose - it's free to slide back and forth in its bracket, restrained only by the bundle of wires. Second thing is that there's absolutely no mechanical obstruction, but it still doesn't work. So, I wait until Tuesday afternoon and call MTH tech support during their limited hours (TWTh, 12-5 EDT). A very helpful tech informs me that the tach reader sliding around is normal, but I should check the smoke unit. The fan motors sometimes short out and when that happens the locomotive won't run. Sure enough, disconnected the smoke unit and it worked fine. PS/3 locomotives don't have a smoke on/off switch, just a volume pot, so the default is "on' when it starts up in DCS mode.
Replaced the smoke fan motor and everything is fine. I have to confess, it would not have occurred to me that a bum smoke fan would keep the engine from running at all, but there it is. Thank you, MTH tech (didn't get his name). I'm posting this just to share the problem and solution, in case the same thing happens to somebody else.
