I have an older Bachmann Brill trolley HO, DC that was running OK a while back but now runs with a high pitched squeal (it's about to get shot off the track! ha ha).

Probably a cracked gear or maybe something got up in the engine? I did put some oil on it and wondering if it ran into the engine?

one of those pancake style plastic engines

I have 3 of the PCC trolleys, one that's older and 2 that are probably from the early 2000's. I bought one at a hobby store and it died and then picked up a 2nd from a collection and now it's died. Both of these were with moderate use. The older one with the pancake style engine still runs but has a split gear. Not very impressed.

is there any way I can open up the engine block on the newer ones to try and see why the stopped working, maybe strip the parts from one to repair the other?