Ignition electrical issue. help?

You should check at a good fast idle, or simulated "low cruise."

EG if the engine is idling slow, the alternator is "just starting to" put out

So if say, the field is grounded, causing "full charge," and the battery is a bit down, you could misinterpret an idle reading for "normal."

But if you speed it up and the voltage climbs up towards 15, you know you have a problem in the field / regulator

The "usual suspects"

Voltage drop in the ignition harness feeding the regulator. That is, low voltage TO the regulator causes OVER voltage at the alternator output

Voltage drop in the ground circuit, IE VR not grounded to battery NEG

Sometimes, battery problems

The mentioned guess, IE grounded green brush causes "full charge" at the alternator

Bad VR, but actually, this is fairly rare.