Two causes come to mind...there are plastic grommet that "smooth" the retract and extract of the window. They may have seen better days. Wore slap out............

Second cause it that the support arms ..the arms that raise and lower the window may be loose in some fashion. There's search area's on the forum that will show you the inside of the door components and you'll get an idea what you're looking at. It should jump right out at you what's wrong once you have the components exposed to your view.

I don't envy you. That's got to be nerve racking !!