assuming you have the same lamp as on my boat, it sounds like you need to remove the clear (or red) bezel to expose the bulb? If that's the case, a small screwdriver inserted in the slot at the bottom of the bezel will allow it to be pried off. If you're trying to get to the switch, I think the reflective plastic piece behind the bulb can be removed to get to the 'guts'.

I think the lamp on my boat is a Guest.

Fortunately, if it's broken, it's one of the less expensive things to replace on the boat...:)

My nav table light also was "broken" in a similar way, and I was thinking the worst, what's the replacement cost. However, I pried the housing apart and figured how the switch worked, and how the whole assembly went back together, always the hardest part, and after two or three tries getting everything aligned properly, voila, it worked again. So "play" with it and you can potentially save yourself some $$.