Carb diaphragm replacement

[akastorm]

I've gotten a couple different carb rebuild kits for my '93 XJ600. They all come with new diaphragms, but I can't see any way to disassemble the black thing that goes up and down to remove the old diaphragms. Mine are still intact, but the rubber is getting a bit stiffer on one, leading to a less smooth motion (if I push it up, it drops down normally then snaps in place at the bottom). Is there a way to remove the old ones, or is that impossible?