Today I had planned to send my Brick (only 192K miles) to the boneyard. But, I had to try & start it one last time. It's been sitting for months & wouldn't you know it started as if I had just turned it off. Sentence suspended. Ok, so I figured I'd fix a stuck caliper (right rear). I replaced it & although all the fluid in the front portion of the master cylinder emptied out of the open brake line; now I can't get a drop to come out when I try to bleed the new caliper. The master cylinder is only a couple of years old. I'm wondering if I'm experiencing a check valve or regulator valve problem. Any thoughts? Thanks.