[lurkingknight]

preengagement = sector gear grabbing piston in the middle of the stroke. This is why teeth 4-6 show greater wear or damage. Once those teeth are gone, 1 and 2 get stripped. This is not your problem.


overspin. gear train cycle speed is so fast such that the momentum of the gears after initial shot is enough to cycle the gears 2-3 more times able to overcome the resistance of the spring. This could be part if not all of your problem.

Cutoff lever. As the cutoff wears down, it is possible that when slow enough the lever will work as intended. When the gear cycle speed increases, it sometimes floats when activated, not hitting the trigger shuttle hard enough to knock it free. Sometimes this issue can come from the trigger contacts being too tight to the shuttle block as well.

Solutions?

check the engagement of the trigger contacts, then assemble a portion of the gearbox including the sector gear and trigger and contacts, turn the sector through the cycle slowly while the trigger is pulled to force the shuttle forward, simulating the firing position. As the sector turns and the cam hits the cutoff lever, the lever should trigger early and the shuttle should reset. If it feels like the sector is turning so far that the cutoff lever is being tripped near the top of the cam, the lever needs replacement.

fixing overspin requires knowledge of shortstroking. You need to increase the spring weight to provide more stopping power for the gear train. This requires a stronger spring that raises fps. Short stroking by removing teeth from sector and piston to draw the piston a shorter distance will reduce fps back to desired levels, but you need to know the exact fps the springs will shoot in your setup, and then remove the corresponding number of teeth.