[Richard]

Not meaning to frustrate you, but I was typing on a soda cracker before.

Let’s step back and look at the potential causes and possible fixes.
One, the opening for the room could be out of square with the most probable cause the aforementioned rivet issue. Take a picture of the opening where the upper trim band is affixed if the skins behind the trim piece are not aligned then that must be fixed first.

If the opening is square, and the room is tilted in the opening, the nylon bearing blocks that the room slides upon reside in the ceiling of the basement. The ceiling “tiles” must be removed to see them. They will be located in line with the stainless runners on the bottom of the slide. They will be located up against the outboard side of the coach. The room can be lifted enough with bottle jacks to replace the bearings or to shim them to align the room.

Third, the room may be cocked from side to side. That can be adjusted with the hard stops that are located in the ceiling of the passenger tire well, and the ceiling of the first bay behind the door.

Pictures of the room opening discrepancies with the room retracted will help tremendously in helping you diagnose the issue.