I just installed my passanger door I got from a junk yard. The widow had a lot of dirt on it from sitting outside and I think it slows the motor down. I think the motor is fine since it doesnt overheat and stop for periods of time. Can I just spray the window with something and clean it off later or just take the panel off and lube it from the inside. Also what to use.

 

Some spray lithium grease on all the channels and guides will work.