suburban rear window fix???!!!

[77chebby]

i'm sorry if this has been a topic before, i tried to search and see first. my rear window on the new burban doesn't work. when i bought it the motor was laying in the back cargo area. i bought a junkyard motor today and hooked it up, still nothing.it doesn't work from the inside switch or the key. could be the junkyard one is broken also, where is the fuse on a 1979 suburban, i didn't see one marked and they all looked pretty good.any ideas on things to check before i spend real money on a motor? anyway to test the motor? thanks, mark.