I would check to see if the pads are pretty worn and if they are installing new pads and making sure they are not binding in the caliper may put the piston back into the caliper and working on a new area of the cylinder.

Sometimes simply getting the piston working in a different area of the cailper will do the trick.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.