97 850R Sedan

Yesterday, after I opened my sunroof, I found that it wouldn't close!

I tried everything I could possibly think of to close it. Tried dropping the motor out, but it's too tight to move the sunroof by hand

I looked in the tracks, the best I could, and couldn't find anything jamming - but it appears one corner of the glass roof sits lower than the rest, when it's retracted.

It closes part way, and then reverses direction like it hit something, or you hit the open button.

My next step is going to be to drop the headliner so I can get a better look at the works.

It makes sense that tracks, etc might be worn, so perhaps I should get a sunroof assembly at the pull a part. What years and models will cross to my car? If it's a wear problem, seems the newer the better....