I verify TDC with the ten dollar tool then I cut a strip of paper & measure/make several marks on it for the marks I need & use it as a ruler to mark the dampener clockwise from the TDC slit with white paint. 0.0632683" around the circumference is (1) degree & four or five marks 10-15-20-35-38 is plenty for me. For example 2&7/32 is 35 degrees. I worry more about the inaccuracy of timing lights in general & I love playing with my dialback but I dont have faith in it's accuracy either but I live with it