Thanks to both of you for your replies.  I actually found another copy of this engine "new in box" on Ebay - we'll see what happens.  Even if it's unreliable, it's important to me to have "my" engine.  If my boys really get into the model train thing, I'll buy them a new, better-quality engine and put mine up on a shelf before they wear it out.

Curious - what does the 4-8-4 nomenclature mean?  In case it's not obvious by now, I haven't played with model trains since I was ~10.

In trying to revive my old train set for my 5-year-old, I'm looking for replacement parts for the above engine.  A local model RR shop suggested that it might have been manufactured by Bachmann for Lionel, which led me to this site.

The markings on the bottom are "c1976 Fundimensions".  The problem is a dead motor, which sits upon and rotates with the front truck and does not apprear to be separable from the truck.

Any information regarding who made this engine or where I can find parts would be appreciated.