Bob - Sounds like you've got some messed up electrics - not at all unusual on an older tractor! Without actually seeing the wiring it'll be tough to diagnose what you've got and how best to fix. However here's a few thoughts that may help you get started: Original Super M was 6 volt. However finding a 12 volt battery in the box doesn't necessarily mean the tractor was converted to 12 volts. Many times a tractor's charging system quits, so someone drops in a 12 volt battery to run the tractor. They then put it on a charger whenever the battery goes flat. The black box you've got under the ammeter describes the original 6 volt regulator (the original regulator has 4 terminals). However unless a part number or voltage is marked on it somewhere it's hard to tell for sure. Also you can pop the dust band off the commutator end of the generator and count the brushes inside. If it's got 3 brushes, the generator is 6 volt. If you find only 2 brushes, it can be either 6 or 12 volt. How is the ignition/starter on your tractor worked? Is there a key or pushbutton starter switch? If so, incorrect starter switch wiring can make the engine fire while it's cranking, then quit as soon as the starter switch is released, just like you describe. Grounding (either positive or negative) is inconsequential as far as starting/running the engine - correctly wired the engine will crank and run with ground polarity either way. Polarity only becomes an issue when you get to the charging system (generator, etc) repairs. Final suggestion: If you are unfamiliar with tractor wiring suggest you find someone who is and have them figure out what you've got now. Once we know what you've got, someone here can then help you get the right wiring diagram and guidance to get it applied.
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