You'll be best to remove the fixtures from the hull and then they can be rebuilt. The lens is glass and can be cleaned up and the socket is replaceable. There are some "slotted" set screws holding it all together but you'll need to clean some corrosion off to see them and use some PB Blaster to get them apart. The sockets can be purchased at West Marine or any chandlery and are a few $$$. Re-use the lens, install a new socket and bulb and re-install in the hull. I did this project on a Tartan 30 last year but only have one shot of the fixture. Could have sworn I took more but they may be hiding on a SD card somewhere...
