just bought a 1999 with same problem. but the sunroof wasnt closed all the way so it is a priority. took the headliner off and found the problem. The cables (think spring steel like a teleflex cable on a boat) are frozen. the way they are made they run through the channels and pick up water and debris. the grease around the gear feels like hand cleaner with pumice. trying some Rust buster now but am sure I will have to heat to loosen them up. If the sunroof is sealed leave it big time PIA