I just picked-up a cosmetically nice Lionel #42 loco and three coaches.
I oiled it, spun the wheels a few times, and put it on my Christmas loop, and..... nothing.
No growls, grunts, sparks, anything. I rolled it back and forth with power on, and still dead as a doornail. ( Just prior I had run my 38 around a few times, so track & power are ok.)
This unit is single-motor, with sliding shoe pick-up.
Am thinking the troubleshooting will be easier if I remove the motor-truck/bogie from the shell.
Not sure how to do it though... there is a stirrup bracket / pivot bolt over top for each truck, but the motor assembly makes this inaccessible on the powered truck...