On the early 220
on the early 220's, there was a problem with the stator wiring not being sealed. If the oil wasn't changed often enough, tiny metal particles would build up and short it out.
The cure was to remove the stator, wash it and seal the wire connecting points with epoxy gel.
That may or may not be the problem, so I will give you all the test data. The issue you are having is that a ground has failed and the connection is only made when you push the starter button or if you toggle the kill switch on and off. This could be a bad connection in the windings or in the CDI box.
The first step is to remove the engine and chassis grounds, clean off all paint or rust and install. The engine ground is always a problem being the silver paint doesn't allow for good contact.
Next is to test the trigger coil / crankshaft sensor. This is a two wire plug that comes out of the top of the recoil area.
Unplug and check with your ohm meter. You should have 100-150 ohms. Next, set your meter to AC volts. Crank the motor. You should have 2-3.5 volts. You will need a decent meter or peak voltage meter to read this.
Here is the coil test.
On the 91 model, you have a charge coils and trigger coil. Give me a moment to upload that data.
That is the CDI test data
There was an ignition change so disregard the early post on the trigger coil. Here is what you should have on the 91 model.
The reading between the B/R and R should be 100-190 ohms. The reading on the pick-up coil should be 85-130 ohms, not 100-150 as I posted earlier.
Where the B/R and R wires solder to the coil is where they shorted out. If you find this reading is off, remove the stator, flip it over, wash it off and seal that connection with epoxy gel.
That should be all you need to test and find the problem. Let me know if you need more help.