Can't remove thumbstick domes, they just spin. What's going on?

I'm trying to replace my bumper switches, but I need to take off the thumbstick domes to do that. I can get them to spin clockwise or counterclockwise, but they do not come off, no matter how much I rotate them. I tried the tall thumbstick, a wrench, a socket screwdriver, and even my drill, but nothing can get the thumbstick domes to unscrew. Any suggestions as to what's going on and how to fix it?