Originally Posted by denby
what should the free length of the spring on the square striker be?
The free length of the magneto drive spring is 42 mm. At each end of the spring is a 2.4 mm thick flat washer. There is also a 0.74 mm flat washer on one end. The trip assembly that I have in front of me appears to have never been apart, so I have no reason to believe that the three washer are not original.
I have been pondering your problem of not being able to get the mag timing adjusted. Spring length and pushrod length are arbitrary to the timing of the mag. The rise provided by the cam and the compression distance of the drive spring determine whether or not there is enough travel of the trip assembly to load and unload properly. One thing I thought of is this:
On the very bottom of the mag armature is a yoke with a screw through it. This screw slides into the slot on the mag rocker. On the screw there is to be a bushing 7.93 mm (5/16") in diameter, which is the width of the slot in the rocker. If that bushing is missing, there will be a tremendous amount of lost motion between the rocker and the armature. That can cause the very problem you are experiencing.