The rear windows have a plate with two plastic grommet that guid the window up and down. They should be pretty much fixed.
I have replace mine. It's not easy but well worth it. Somebody else on the forum told me to go out and buy shower door rollers, the ball bearing type.
You drill out the log and bolt in the rollers, they are a perfect fit in the track. I put new grease in the track and they work a treat.