Worst case is a broken lift angle from never lubricating it. More likely it just needs to be adjusted for wear.

If it works hard and looks crooked moving back and forth, its the lift angle, expect $500 or more to fix (less if you do it yourself).

The sunroofs don't actually seal, there is a drip rail and drain system, so water won't get in even if the roof panel sits funny.

Front edge should be slightly lower than roof, rear edge slightly higher (about 1 mm) to eliminate wind noise.

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!