I would taKE THE BLEED NIPPLE OFF AND SQUIRT STUFF IN THERE, and again a few days later, maybe tap agressively around the cylinder where the piston is seized, if you are going to end up gettin a new one if this fails might as well have some fun. If after a few days/weeks of fooling with it using comppressed air from the bleeder side etc it still doesn,t want to move, maybe a little time in the oven would do the trick. I actually really enjoy the ridiculous challenge of "fixing" a part that I could just as easily replace. I also seem to enjoy the negative savings involved with rebuilding something that considering the hours invested, even a minimum wage, I would be better off buying