Need moon roof help on yukon xl

I was driving my wifes yukon last winter up in canada, well we were going through a BK drive through and they had a low height limit, I had my ski box up top, so I open the moon roof to get a looksie to see if I would clear or not, well when the glass opened it went back too far and caught on a metal roof support which in turn made it not close again. Needless to say, it was raining out and I was stuck with a hole in my roof. So my buddy and I drive across the street to canadian tire to buy some tools to get the headliner down. After spending most of the morning screwin with it we got it to close, but it didn't go all the way forward automatically, I had to hit the switch again to get it to close all the way. If I try to just open it up it doesn't go as far as it used to. It acts like it jumped a tooth on a gear and goes too far back but not far enough forward. I don't know how the motor drives the glass but that is my thinking. Any one have experience with these? I haven't taken the time to pull the liner all the way down to see what is going on with it yet, figured I would ask first so I don't have to tear it apart again to fix it.