Generator Test

When you ground the "F" terminal with the engine running 1/2 throttle or more, the voltage should climb past 7v. You can test the generator without removing it from the tractor. Remove the belt and with a piece of heavy wire connected to the NEG or hot side of the battery, the generator should spin like a motor. While motoring, ground the F terminal. The gen should slow down, but continue to spin. If all that happens, the gen is ok. Then it's a matter of testing the wires between the regulator. I use a headlight bulb for this test. If each wire can flow enough current to light the headlight, they're ok. If the wires all check out, replace the regulator.

Before you replace the regulator, verify that the BATT terminal on the regulator has a good connection to the hot side of the battery, also remove any rust from the mounting tabs on the regulator to the tractor. Wires can complete the circuit, but if only a strand or two are intact, it can't carry the current for the system to work. That's the reason for load testing each wire with the head light bulb. You may have a faulty regulator, but you may also have a faulty wire. The load test will confirm the wire, the motor test will confirm the generator's condition. If the wire and generator pass each test, then you can be certain you are replacing a failed part.

Jacob, in 80 some years a tractor could be either pos ground or neg ground. The starter does not care about battery polarity, only the generator. When you get to the motor test on the generator, you are also polarizing (telling it which pole is ground) the generator. I recommend testing all wires with the head light bulb. Remember, in all those years it's likely to be spliced and broken, generally in bad shape. Unhook both ends of each wire and then put each wire individually in a circuit with the headlight bulb. The reasoning is if each wire can carry enough current to light the bulb, the wire will work for the generator. Remember, voltage and current are like water pressure and gallons per minute. A small hose (thin wire) flows fewer gallons per minute (amps) tha a large one. Having something like all of the strands in a wire broken except for one is like kinking the hose. Less current flow less water flow. A volt/ohm meter would be like a pressure gauge. Since a very tiny amount of current flows through an ohm meter, you would see a complete circuit with little resistance. What will get you is when the amperage needed to operate the load in the circuit (headlight bulb) can't get through the single strand of wire.

Glad I could help. Just remember to take it one step at a time.