Here in the rust belt..... some of those pistons can be really hard to remove. What I have done is drill a hole thru the piston(s) you are having trouble with, then tap threads into the piston. Screw a "long" grade 8 bolt with the end rounded off nicely, into the new threads, all the way in, keep tightening, this will push the pistons out. Use penetrating oil around the piston also. Drill piston in center. It works for me
Dave
