In replacing the two cabin light bulbs with G4 LEDs from Marinebeam, I found it almost impossible to remove the brass+glass covers to get at the bulb. Seems the factory or a prior owner really tightened down the three screws holding the fixture to the headliner. It is very difficult to get a hold of the cover and rotate the cover to release it if the screws have been overtightened! After a full hour of wrestling with just the two dining lights I finally had success.
Getting the old bulbs out was easy but I broke one of the new LEDs trying to wiggle it side to side to get the pins into the connector. Lesson: be gentle but firm in your efforts. Like many maintenance projects, this one took way more time than I expected. I have completely given up on the idea of replacing the five main cabin light bulbs with G4 LEDs.
On the hook or at mooring buoy we will be using the only two dining lights and not the main five cabin lights.
On the flip side, replacing the anchor light bulb with an LED bulb took less than five minutes. Very easy.
My only tip here is that if you have over tight brass and glass cabin light covers and manage somehow to get them off remember to back out the three small screws holding the fixture in place a bit to make the cover easier to remove next time!