jimmy rear window problems

[passthebuck]

I'm a 67-72 guy BUT my buddy has an 87 jimmy. I'm tryin hard to get him to join this board but he's too "busy". His rear window wont roll down. You press the switch to UP & you can hear it try to go up, but it obviously cant go any further (its up all the way all ready) BUT it will not make a sound when you hit the down button. It's a brand new switch in the dash. Do these motors go bad often? or is it the wiring ir a poor connection? I just thought you guys whould see this type of thing often & mabe have an ez answer. I'm going to help him out when its a bit warmer & get 'er goin. Thanx for your help.