There are a number of ways to get the servo (apply pistons) out of the bore. Its the seal that is sticking, usually not the aluminum piston itself. Dont even think about stick anything sharp in between the piston and the bore. You scratch up that bore and it will never work correctly again. Spray some penetrating oil in there from the topside and soak it real good then let it set for an hour or so. This usually does the job. DO NOT USE BRAKE CLEANER! You likely will need to replace seals if you arent doing the corvette servo install. The originals likely will not have replaceable seals but instead molded seals. Not sure what you are trying to accomplish here so.......
