[decooney]

Phil,
If its an original cap, it could be corroded/siezed in there a bit. Is there enough surface sticking out to get some channel locks on it to twist it a bit before pulling straight out? Or, is it one of those dumb flat aftermarket caps? If you waste the cap, just get new ones at Kragen or something. Worst case, drill a small hole in it, screw in an old style dent puller and yank that F%^ker out! Ha. Good luck.