I'm with Zepplin here and would like to learn more about the "U's" and "J's". I'm guessing the stroke being described is a rotation with the wrist as a pivot point and while moving the the blade forth or back on the plane of the stone, and while dragging it in the "X" pattern to get the entire edge dragged across the stone, one pivots the blade to get the toe to lead the stroke - all the while maintaining careful contact with the stone so that all movement stays on the plane of the stone surface.

close?????, Bruce