5. The position of the screw in frontview. You have to adjust the position between 9 and 11 o'clock. Depends on the range of focus you prefer. Put A and D on the lens again and find out what position you prefer. Drill the hole (2.5 mm) 19.5mm from the front of part A. Do this very exact. There is only a small ring where the tubus is thicker. Cut a 3mm winding.