I've just purchased this same engine.  A few issues with the drive wheel wipers not making consistent electrical contact.  Did you ever replace the traction tires?  I'm thinking I might put a second set on the rear drivers to try to give it better pulling  power and help the front guide truck seated on the track when in reverse.

Is it possible to add a current keeper (keep alive capacitor) to a new American 4-4-0 DCC that has the sound value equiped decocoder?  Would it fit in the tender or does it have to go in the engine?  Thanks.