Get some Kroil, soak it for a few days, than warm up the area around the piston with a propane torch. Don't overdo it- - - -just hot enough to make a drop of water sizzle when it's dripped on there. It should free up, but if you've already buggered up the piston, you might have also damaged the housing. I think I've got a couple of junk Rochesters. Email or PM me.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!