This video will show you everything you need to know, in far greater detail than you'll find anywhere else. It's a three part video, I've pasted a link to part one, the others are linked from the first.
I did a full sunroof rebuild so all of it was relevant for me. It's possible you only need to follow some of the steps. Lastly, while my car is a 1984 and has a slightly different design than the earlier model, the parts are identical enough to do what you need
https://www.youtube.com/watch?v=5TD-DeF2jTg