Power Windows

The drivers side window on my 91 Bronco is not going up. The motor is trying to push it but it doesn't go up. I was looking for parts and saw that the regulators are sold separately and I was wondering if this might be the problem, or if it is the motor. Also on the passenger side, if I roll it all the way down and leave it it will not roll back up. I have to take the door panel off and adjust the screw on top of the motor(don't know why this helps???). If anyone else has had this problem anyhelp would be greatly appreciated.

Yeah, I'm having that same problem on my Passenger side window as well, seems like the window is off the motor. I can hear the motor going but the window won't go up without guidance, and then it slips a few inches afterwards...