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.
Another possibility would be incorrect diamond wire tension. In order to use the same SC17 aluminum section, the SC22 is rigged with two diamonds and one crostree - or at least this is how the one here is rigged. The mast may twist if any of the eight turnbuckles -one for each wire section- is too loose or too tight.
