I bought an old but operable Chicago Pneumatic rivet squeezer on e-bay. Now that it is in, the dies that go with it appear to be too big. I can change the yoke no problem. The question is whether I can change the piston. Is it possible to buy a new piston that is the correct size to fit through the smaller yoke openings for the appropriate dies, or do I chalk this one up to a learing experince?