I know for a fact I have a seized caliper since I have to push the piston in with a C-clamp. I recall being able to do this by hand. I'm wondering if it's the caliper assembly or something in the brakeline (proportioning valve). I'm taking apart the caliper tonite to inspect it. I'll probably replace it with a good used one from a junk yard instead of wasting my time overhauling it.