Zeke
I received a WSM from Joecdeere to better understand your tractor.
It's charging system is not like a GM or normal alternator but rather a dynamo.
The difference being with a "normal" alternator, the magnetic field inside the alternator is produced by coils of wire and the regulator varies the amount of current flowing through those coils of wire to change the alternator output whereas inside a dynamo, the magnetic field is produced by real magnets and thus there is no control of what is happening inside the unit.
The dynamo is sized to match the expected electrical loads on your tractor and if and when there is too much current, the excess is turned into heat and dissipated by the regulator fins.
The Alternating Voltage output of the charging unit needs to be verified.
Do you have a multimeter and are comfortable using it. The ones adequate to help you sell for less than $10 like this one from Amazon.
Set multimeter to measure AC voltage with a scale of 200 volts. On the meter I posted, the correct position one be one more step to the right.
Disconnect electrical plug at dynamo and connect test leads. At full engine rpm's you should read 40 volts or more.
The WSM is excellent. If you will do the first test I suggest I will have figured out the next one you should do.
Dave M7040