Avenger F1000 suction problems

[photo_doug]

New to the forum so first, hello to all the photographers out there. I've got a couple of Avenger F1000 suction mounts that won't hold suction. I've gone so far as to pull the plunger, inspect and clean the plunger o-ring seal. The trouble seems to be the little flapper valve at the very back (front?) of the piston. If it works like most flapper valves, it should allow only air to pass in one direction. When you blow or suck air through the cylinder the valve the air seems to flow both directions...in other words the flapper valve doesn't seem to be working. My guess is it's gotten dried out and stiffened up over the 3 years I've had the beasts but I can' believe a .20 piece of rubber is going to make me buy a $70 part again when It's the only thing wrong. Has anyone seen similar with these things or been able to fix this problem?

Thanks,
Doug