Also, that's not a piston, it's a button filler. It probably doesn't move because the latex sac has completely solidified. A new sac should fix it. It's usually a cheap and easy fix, but I'd send it out if you're not familiar with it. There's a science to sizing and trimming the sac, and you'll need talc and shellac to install it. Also, I find the gold plating on Wearevers to be super thin. So I wouldn't have them buff it.