Mine did the same thing a while back, it was the sliding jaw. The good news (if this is the problem) is that the part is about $10.00. The bad news is that you have to remove the entire window regulator and basically mash the metal head of the new sliding jaw into the location of the old one. It is MUCH easier to just replace the entire thing (about $100.00.) If the motor still makes noise, the fise and or switch is still good. Pull the door panel and see what's going on.
justin