Loco stopped working

[sandy_lang]

I have an OLD Bachmann loco EMD F9 - Canadian Pacific - 1455

It was working fine for the past ten days, running around the Christmas tree, for about 2 hours each night, on a Kato M1 set loop. Last night she just gave up, tripping the breaker on my Kato power pack. Reset - same. Reset - same.

I took the loco apart to the extent I could but could not figure out how to get the trucks off (there is no video anywhere out there on this sucker!) I tested both trucks by putting one on the track and lifting the other end of the loco off. I get a hum for about a half a second and then click - the breaker trips again. Same thing for both trucks. I can crank the power up to full with no loco on the track and the power pack stays green.

Thoughts?!?