[Post in Progress] I have observed that the rotation in the arm can never be on the central axis of the limb. It must continually switch between the ulna and the radius.

If it is on the central axis, there can never be any “gain” on the opponent, as the fixed point is not at the right places. In this case, as one of the bones rotates towards the opponent, the other is pushed out. If the movement is done this way, it is impossible to match the opponent’s push. What happens in this case is that the practitioner’s fixed point is not at the right place and causes spinning without spiraling.

Now the question I have is how this relates to the rotation of the trunk. Is there a parallel? Is the central axis the axis of rotation or is it the axis formed by the connection between the shoulder wells and the kua?