As I recall, I had to remove the trim boards on either side of the top in order to adequately access the mechanism. A solid step stool helps. Gently sneak a knife blade under the wood plugs in the trim and pop them off so you can remove the trim retaining screws. Many coaches use square-drive screws, so have 2 sizes of square-drive drivers or bits on hand. A strong penlight helps so you can see what’s going on with the rail and door hangers.
I think one issue with ours was a loose screw or two holding the track to the ceiling; the screw was snagging the mechanism as it tried to pass, knocking it off the rail. It’s been too many years, but I probably either used a longer or wider screw, moved the screw downrail to where it could grab better, or used glue or locktite in the old screwhole.
Joel