Appreciate everyone's comments.  The front trucks were reversed and shorting everything . Jim and Jonanthan's comments and solutions worked perfectly. Maybe Virginia will have a Christmas village afterall.

It is a diesel.  Union Pacific 866. Purchased in the mid 80's. Performed flawlessly but sparingly until this recent incident.

Jonathan, thank you. I will attempt what you outline.  I have made a mistake in my description of the locomotive I guess. I don't know if that make a difference in the problem or potential solutions.  This locomotive does not have a tender. It is only the locomotive. It has two trucks with 4 wheels each. I guess that makes it a 4-4 not a 4-4-0. The rear truck under the motor has two wheels with bands around them . I assume these are the drive wheels.  The front truck does have wipers and is wired to the light as you indicate. Now I also guess that the plastic cowling could be flipped and the "front" placed over the motor but I looked up some photos on the Bachmann site and it appears the motor should be situated in the rear of the locomotive.  Apologies to all for my amateurish descriptions but your advice is very much appreciated. 

Jim and Jonathan, thank you both for your input.  What you say makes sense although I know little about electricity. The rails check out ok with a continuity meter.   The front trucks got knock out in the accident and I may have inserted them backwards. The motor is in the rear and although it was not knocked loose, I suppose it could have turned 180 degrees.  I will  reconfigure and try again. I will also try the wheat bulb test.  This is an old model 4-4-0. I do not think it is a Spectrum but I really don't know how to tell. The loco has pickup wipers on both sets of trucks.

The transformer does not have a short or overload light BUT It is tripping. I can hear the click. It resets itself in a couple of minutes and clicks again.

Here's another question/observation. I can see the red and black wires running to each truck.  Should I configure the trucks so the red wire is on the same side on front and rear ?

I have a similar problem. After my HO locomotive hit the floor. I inspected it and could not find any thing obviously broken. Now I place it on the track and nothing happens.  If I lift one end the motor begins to operate. I sit it back on the track and it stops. I lift the other end and the motor begins again. I am a newbie. The engine is a Union Pacific #866 . I think a 4-4-0.  sounds like a short but I can find nothing. Any ideas from the group ?