Help please! The sunroof moves back a couple of inches and hangs up. It cannot be moved back (open) using the manual crank. The indipendent mechanic I went to told me to take it to the MB dealer, that the only way to fix it is to get a new sunroof... I would like to open it up and take a look see... How do I access the mechanism? And, what's the degree of difficulty?? Thank you for any suggestions.