High voltage?

So your regulator is not working. It needs to be replaced. If you get one from Massey it will be plug compatible. Regulators of many types will work but you need to have significant electrical savy to make a different one work successfully. I've gotten 6 volt mechanical regulators to work at 12 volts. I've gotten mechanical regulators to work with alternators designed for a solid state regulator. I've not been successful in mixing and matching electronic regulators.

Since you have adjustment screws, it sounds like you have the mechanical type of regulator. Make sure the contacts are clean and not pitted and that they move easily - press on them with your finger. You can reduce the tension on the spring of the regulating coil to reduce voltage. The other coil is a voltage sense coil and seems to be working ok since the charger (alternator or generator) is working. If you can't get the charger coil to flucuate continuously and reduce the voltage, I'd replace it with the current MF part.