Voltage Regulator and low output from Alternator

We are confusing each other. Let's step back

You need to get this thing on the bench (if you do not) and check it

Check EACH brush to ground that is the alternator case. Should be "open," or infinity

Now check from one brush to the other. It should NOT be a dead short, but rather up in the 2--4 ohms or so between the two brushes

What I'm very concerned about is that one brush is either UNintentionally grounded, or has an intermittent ground. This could have ruined your VR, and may ruin another or worse, burn up some wiring. That circuit IS NOT fused