gjensen

My antenna base is loose so I wanted to remove it to tighten it up. My trusty (laugh) Chilton says if it is an expedition, I just uncrew the mask (didn't need a manual for that) and undo the three base screws. Problem is that there are no visible screws. There is a plastic cap of some sort, and when I feel underneith, I can feel two screws (one on each end). However, I cannot pry off the cap. I've actually bent the body sheet metal trying to pry it off. The instructions for the F250 (in the manual) say to pry off the cap to reveal four screws. But this is two screws, not exposed, and a cap that won't come off. Any recommendations before I take a sledge hammer to it? I'd be happy to break the cap off and get a replacement but I can see I'll do more body damage with a larger screwdriver. The cap actually has a slight amount of play with whatever is holding it, so it is not frozen on or anything like that. Help is greatly appreciated.