Finally. It is unblocked. I used the bend and washer method to start with but it was taking too long so with a friend we tied two ropes, each fixed with 2 knots, to the mast, one on each side of the joint. then we stuck a piece of wood in each and twisted them up. This gave us enough leverage to twist the mast free, but it was still hard work.
As of now I will be paranoid about any grain of sand in my joint.
JP Super-X 106l, North F8 Ram: 5.8m,