Okay, this is my first post and I feel a little dumb asking this question... but I am honestly baffled. I have a 1984 Starcraft Starmaster 21, with interior lights mounted on the ceiling. I need to replace a bulb that has burned out... but I can't, for the life of me, figure out how to get the lens off the fixture so I can access the bulb. The roof (being so old) seems like it might rip if I push/pull/twist too hard, and the lens is hard, like glass, so I worry about "pinching" or "pulling" it and breaking it. The picture (and arrow) point at the type of fixture I am working with... small, square, with a sliding switch on the side. Any help is MUCH appreciated! I look forward to being an active member of this community!