After the cleaning+ suggestions, here’s another technique you might try.
First, get a good reading on just what part of gasket/seal is leaking. I did this by looking at/thru closed hatch seal, using a mirror and good light conditions….I found light outside/dark inside [while looking from inside] best. In this way, I could see small gaps, maybe 4 -6″ long, where seal wasn’t sealing.
Fixed this by inserting a few short sections of once-folded aluminum foil under inner edge of gasket. Has been fine in the ensuing 5+ years.
C 380 #44, My Bride II