have you tried jamming it upside down in a grid outside and twisting the whole frame? managed to free my post recently doing that, didn't even wreck the clamp just bit into it a lot
not specifically, but i have had a 10ft long pole attached to the top of the post and couldn't get that to move...i've even made a 'post puller' device thing - that didn't work either.
i think cutting is my only option at this point.
whatever i put in is going to be an upgrade compared to something that doesn't move.
probably going to get a deda for matching collar and cuffs.