sunroof
i had the same problem with ym sunroof. it ended up being the track on the drivers side, vw likes to use plastic in a lot of places they shouldn't. you can try pushing up on the back when you open it up to take the stress off of the little ramp that makes it go up. when it is open look at both of the tracks inside and see if they are cracked. they are actually pretty easy to replace.
i had the same problem with ym sunroof. it ended up being the track on the drivers side, vw likes to use plastic in a lot of places they shouldn't. you can try pushing up on the back when you open it up to take the stress off of the little ramp that makes it go up. when it is open look at both of the tracks inside and see if they are cracked. they are actually pretty easy to replace.