Hi. Having the same issue on our 70. As I was cleaning out the outside frame and area between the hinges, frame and shell, I noticed that there is slight minimal separation between everything that is sandwiched together. I know when putting the frame in against the shell, butyl tape was used. Then it was riveted into place. The butyl tape gets brittle on the exterior with age and weather. I'm thinking this is where our leaks are coming from..
So, I scraped, wire brushed, scraped, cleaned off and sealed the separation with lexel sealant.... Hoping for a good rain later today so I can sit and see if it worked. This lexel has worked wonders everywhere we've used it with proper prepping and application... I'll post back later...