Not sure if it will help in your situation but try rubbing a bit of Vaseline on the gaskets. It stopped the leaks on a couple catamaran escape hatches I delivered.
Vaseline over a period of time will degrade rubber and variety of rubber like petroleum based products. It does work well short term though. Food grade silicone grease is probably the preferred choice. It is available at plumbing shops, used for lubing faucet cartridges amongst other things.