Hello.  I got my PO15 running (for 20 seconds on the stand) and couldn’t shut it off without grounding spark plug out with a screwdriver.  I didn’t run over 20 seconds because of no cooling. I removed and cleaned the switch contacts and got continuity at the 2 prong connector.  Got continuity to points while holding in switch. But it still won’t kill spark.  Then I discovered (through a friend) that a ground wire is missing from the mag plate to the 2 prong plug.  Question is where does “missing “ wire connect to the mag plate?  The only wire I have under flywheel runs to the points.   Thanks for any help.  I’ve never ran this on a boat so stopping would be a great feature.   Brian.