Mine stuck up on the right side. What happens is the guides are plastic and break. I unscrewed the glass and worked the sliders down and screwed the glass back on. Because I wanted a sunroof, I went to the Sunroof Doctor. They remake the guides in aluminum and a return kit for around $125. I decided to get the whole using for about $395 minus $100 core. They send you the box you replace your sunroof and send the old one back. I was very satisfied.Still have the car. Its easier to replace the ntire unit than use their kit after talking to them.
It's not hard to change the whole thing out. The headliner panel is a pain but really not too bad.
Here is the link, search on Lumina/Monte Carlo
http://www.sunroofdoctor.com/
Corndog...