on most if you remove the inside trim panel you will see four long bolts that squeeze the inside mount plate and the outside plate together. I would first make sure they are snug, then shine a bright light up around the seal area and look for signs of water movement, you could have a piece of twig or something under the gasket,.
if i remeber right the a/c needs to be lifted up to replace the gasket.
USN Retired, Life time member of the DAV.
Enjoying the 2008 Damon Tuscany 4056, no your eyes are fine, there are 6 slides