A little WD40 may help. I remember I used PB Blaster, but I was also replacing my foams, so I didn't care if it soaked into the foam rubber.
Just push it all the way down and give it a good snatch up. It will pop out. Just watch your face... don't ask me how I know! lol! /ubbthreads/images/graemlins/rolleyes.gif