Did the exact same couple years ago. The grey moulding is actually just painted on the window.
- remove the interior trim, only held in with 2 screws
- remove the lens, you'll have to cut and carefully pry to get it separated from the caulking or use fishing line trick
- scrape the remaining caulking off the boat and lens with a plastic paint scraper
- clean with acetone and then clean again with soap and water then water. And then clean again with soap and water then water. Dry well and allow to air dry Make sure all the acetone is gone otherwise will leak (( trust me on this step
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- tape off the boat and lens inside and out to stop squeeze out from sticking
- use DOW 795 caulking ( nothing else will work) and apply and large bead
- reinstall the lens with the 2 screws, you should have 1/8" bead left between lens and boat and flush or slight squeeze out
- clean up squeeze out with wet finger and leave smooth surface.