The link you provided explains the v/r adjustment correctly.
Pay careful attention to this adjustment: “ If it has the arm, adjustment is made by bending it. Increasing the spring pressure will raise the voltage setting. “
Do you set your ignition points by bending the arm? No, they have an adjustment screw. Because over time , bending doesn’t work.
And another critical piece of information: “ After the settings are done the cover needs to be replaced and the voltages checked again after the regulator temperature has stabilized.”
In other words, when the tractor is good and hot, you will need to remove the cover and quickly make more adjustments.
You will also need to keep checking your voltage output every few months because it will change with both time and temperature. Remember, it’s only .about 2 volts that makes the difference between no charge and a boiled battery.
IMHO…….cleaning up the grounds, replacing the cables and buying a new 6v battery is a lot easier.