In taking another look at your pic it looks like the green wire is not cut, but loops around behind the frame and connects to the center terminal on the regulator. Pictures are worth 1000 words as they say, but clear and precise pictures are worth more. It is impossible to see all of the PO's wiring artwork in one pic, although the hawker bunch on the forum see's a lot in your pic.
I was mistaken on the solenoid wiring and the loud one's post is correct. The ignition does feed B+ to the handlebar engine stop switch , then to the momentary starter button, then on to the starter lockout switch (on the clutch lever, not all models), then to the starter solenoid coil which is permanently grounded on the other side of the coil. . Some systems use a green wire for the grounded pole, and black for momentary B+ coil side. The starter solenoid looks to have been replaced at some point (taped connections) . It more than likely had the same problem long before you acquired this gem when the solenoid was originally changed.
This snip from the manual shows the solenoid, the black / yellow ground, and wire from the interlock switch.
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