From what I've seen the problem is the rotation of the mast is controlled by how tight the main sheet is. If the lower batten/boom isn't set up right or if the main sheet isn't hooked far enough forward on the clew plate the mast seems to be over rotated all the time.

A guy here solved the problem by adding a rotation bar to the mast just below max down haul and runs a line from that to the clew plate. Now he has control over how much it can rotate.