2002 Jeep Laredo Power window

Power window stuck in the icey weather, I tried to open and it straind, made a little breaking noise (plastic breaking) came down partially, half inch approx and then would not work.
Upon removing the trim and examaning the mechanism, everything is working, window will go up and down, but needs a hand to move up smoothly as it wants to tilt slightly to one side and this causes it to strain. I found the plastic part that snapped in thr bottom of the door cavity and it looks like a plastic beveled piece (white) that attaches or broke away from somewhere? That helps the window glide smoothly on the track my question is. Is it attached to the window track, or the motor mechanism and can it be purchased seperatley and can you tell me where it attaches and what the part number is. If you need a picture of the broken piece I could probably do that
Thank you