Phil: Thanks very much, that's just what I was looking for. The screw and the little coupler with the crimps come out of mine easily, but the pad is jammed in.
DC31k: Thanks for the link. The tail of the vice slides freely in the boss, it just won't go past the end of the clamp pad.
I suspect I'm going to have to file down the round section at the end of the vice tail so that it will come out of boss. Then hope that I can get at the clamp pad with a Dremel bit to get rid of any burrs and somehow get it out. Might need to then drill that little couple for a couple of grub screw to hold the pad in place again.