We just purchased a 1995 Hunter 23.5 (sails wonderfully, especially in Charlotte Harbor, FL where it can get shallow). We have three cabin lights below and they don't work. The battery hookup is fine. We can't get the covers off the lights to replace the bulbs. It looks like it should be a "smoke detector" type of installation, but they don't unscrew or pop off. I don't want to pry them off as that might destroy the unit. Any suggestions? Many thanks.