'85 Suburban Rear window won't raise

[JohnnysCamaro]

Hello all.
My liftgate window is stuck in the down position. Switch works, liftgate closed sensor switch works. When I press the Window up switch, the voltage dips (lights dim, ignition buzzer drops, you can tell there's a load on the battery, the lift motor sounds like something is gonna happen but the window doesn't raise.

If you slam the liftgate hard with both hands on the right SOMETIMES the window will raise, but won't raise anymore. I've read others on this board who've said if they go over a bump or kick the tailgate real hard in the area of the lift motor it will raise but so far mine isn't doing anything but aggravating me. LOL.

I removed the upholstery cover and metal panel and saw the window, motor, lift arms, etc. I sprayed crank creep through a skinny barrel and tried to lube up the gears, etc. to no avail. My guess is that the grease is so caked with dist and dirt that it's finally quit. One thought I had was to hook up my jumper cables to my newer suburban and see if the extra shoot of electrical juice might break the motor loose. I have even sprayed Electrical contact cleaner through a skinny barrell on everything I can see.

If that fails whats the best way to raise this piece of glass?

THanks all,

Jonathan Smith
Greensboro NC