sounds like the motor took a dump or the cable is locked up. they cut through the guide/sliders, or it just frays and knots up the cable inside the motor.
replace it. you want a window regulator, dont waste your time with one with out a new motor cause you think your maybe good still, not worth it when it fails.
junk yard regulators are cheap and last a while most of the time. oem is better then the after market for these.