One parking brake won't release Options

[PinetreePorsche]

My '73, in pretty good shape, although the pass. side parking brake was weak-- badly out of adjustment. Brake held pretty well with mostly the drivers side. All pads in fair shape. I parked it on the more steeply sloped part of the driveway last week, didn't use it for a week (not unusual-- sometimes it well sit 2-3 weeks), and when I started it and put it in gear, and released the handle, it wouldn't move. If its in first, it tucks down at that wheel-- ie compresses the suspension; if in reverse, it rises up on the suspension. I don't think its a rust-frozen cable-- never any cable hang-up before, and I lubed it as best I could last time I was into that wheel. I did pull up the brake handle extra hard when I parked it, maybe got one more click on it than usual, when I parked it. Haven't jacked it and tried to get the wheel off, partly because it's on the slope, and would need to be cabled or chained to my van parked in front to assure it doesn't slide/roll/slip downhill and fall off the jacks, although I'm willing to do that when I think I know what I'm going in for. I wonder if something inside the wheel could have gone "too far" and jammed? I assume the tuck or rise means something to someone very familiar with the weird rear calipers on the 914. Any ideas?