I have a ProXL it's a 1998 I think, but anyhow, it has 3/4" screw in posts. In this case, I cannot get it to screw out. I put a pipe wrench on the seat post at the bottom, it moves, I've turned it 4 or 5 revolutions, but it has not gotten any looser or higher. There is no access to the bottom of the post plate. Anyone here had this issue? It looks like I will have to remove the screws that hold the plate to the deck. I took one out, two others are just spinning. I need this post, my partner is 72 and he can't tap dance any more.