My Volvo 740GL driver's side window won't go up after rolling it down to where about 1/4 of the window is still up. Rolling up from that point the window crank feels like it's skipping. I took the door panel off and when the window is down it looks like the gear that's spun by the window crank isn't making almost any contact with the big gear that rolls the window up. What can i do to fix this?
EDIT: When the window is more than 1/4 up the gears still skip a bit but still roll the window up. When the window is 1/2 way up the gears don't skip and work just fine.

 

Sounds like you may have a few broken gears on the unit. They sell replacement sector gears .

 

You have worn out teeth on the window regulator - the only choice is a replacement. ( unless you can weld some new teeth back on) You will need the 2 (blue?) plastic squares that go between the window and the regulator.