My girls 95 gt driver power window is acting up. The window was jumping up&down while going up/down, now its up but does the jumping thing and goes nowhere usually. Looking for what part could be bad, so I can go ahead and order/replace for her.
The plastic rollers that ride in the reg tracks can be problematic.
And the nylon bushings in the motor are a wear item, especially if a window has not been moving smoothly (the bushings act like a torque-clutch).
You'll have to remove the door panel and do some looking.
I had this same problem. If you can hear the regulator running but the window doesnt move, thats a pretty good indication that the bushings inside of the regulator are bad. Mine were, so instead of spending good money on a new regulator I spent four dollars on the bushings and now the window works good as new. Sometimes those regulators are a pain in the but to get apart. And putting the new bushings in isnt that fun either. Good luck