I have a 1994 C180 Euro and it had a very stiff sunroof which moved very slowly and struggles doing this. The battery was old, so I changed this and it moved a bit faster, but still wouldn't tilt. I took it to a Benz dealer and they simply slushed a lot of that magic Benz grease along the rails and sides. Now its moving as smoothly as new and it now tilts and untilts without any fuss.
I guess you have to try this before you do anything surgical and dig up everything from the roof. Was told it takes a lot of time and patience. You have to be very careful you don't cause more breakages doing it and while you are reinstalling everything. The dealer here charges about A$1200 to do the whole job including replacement parts. The greasing cost me only labour, about half hour and the grease.
With those noises you mentioned, it seems more like something is very loose, broken or damaged in there and may require some surgical work to be done on it.