Welcome to the forum.
The real question is why has your door remained working for so long without repair?
The repair is "easy". Please remember that those curved panel doors are made from Unobtainium, so use extreme care to not damage them, especially while removed.
The common issues are track crud, followed by truck(s) failure.
For the track crud, what has worked best for me on decades of ownership of my 2000 380DA is to flush them clean w/ plenty of garden hose water. I do that each time I wash the boat. I also vacuum the track when vacuuming the salon.
When the trucks fail there are two sizes of trucks used on this boat, 23mm and 25mm. They also sell a 31mm, but those are not used on this boat.
https://www.fpmarine.com/Sliding-door-track-rollers-p/door%20truck%20a%2023mm.htm
https://www.fpmarine.com/Sliding-door-track-rollers-p/door%20truck%20b%2025mm.htm
Replace failed trucks w/ identical size parts.
The panel between the door and the windshield is retained w/ Christmas tree fasteners and must be popped off for the service.
When I am doing this service part of the process is to remove the tracks. When I replace I squirt sealant into the holes.
