Benzair

Hey guys, new member here with a new to me 07 ML320cdi. My sunroof works properly except for the shade. It won't move independently from the sunroof. With the roof closed I should be able to slide the shade back to expose the glass roof but it will only move a couple of inches and seems to bind on the left/drivers side. Any ideas or a diagram of the whole unit might help. I'm guessing it's out of it's track somehow. Being a new member thanks in advance for the info on this site.