Switchers stalling? Please no.

[FCIN]

Back to the switcher stalling problem. One of my favorite DCC/Sound equipped locomotives has suddenly started stalling and intermittently experiencing sound resets for no apparent reason. This is one of the outstanding Atlas MP15dc models and has, up until now, been very reliable. The wheels are not dirty, nor is the track, so I'm puzzled. I can't see anything in the trucks that might be causing this. None of my other DCC/Sound equipped loco's have experienced this, even an inexpensive Bachmann ALCo S-4. Any ideas on what to look for or suggestions? I sure don't want to have to put this model in display only mode!