On my 78 bronco, rear window did not work unless I did it by hand, replace motor I can hear it run but window don't move on it's own although it's much easier if someone holds the switch as I move it by hand. I removed window and still motor will not move regulator on it's own. I have cleaned up and greased the regulator will no luck. Could I have a bad motor or what? Should I unbolt motor from regulator and see if the gear turns when I flip the window switch?

 

That is a pretty common problem. There are plastic internal parts in the motor and when they wear out the motor still spins but doesn't work properly. There is a place that sells a rebuild kit with metal parts or you can replace the entire unit.

 

Try to lube the weatherstriping gaskets. I use silicone on my 1990 rubber.


There is a plastic gear in the motor that has grease in it, take it apart and inspect and regrease.

 

I'm sure you fixed it by now. On my 93 bronco I ended up inspecting the gear drive attached to the top of the motor. The 3 plastic pieces inside had exceeded their useful life. I dropped 3, I think 1/4" nuts, in there place. Greased it up good and It works. Easy fix. Less than a half hour. Read about it on one of bronco forums. The guy was real sharp.