Another quick test without removing components would be to physically move the VR through it’s three positions. Take the VR cover off and with something non-conductive, (toothpick works) move the arm that holds the center contact to engage the full charge contact, the grounded contact, or keep...
Yes. With no ground, it would still deliver resisted voltage to the alternator field (F terminal) and would charge as in middle position.
I'm just thinking I may have better described the three positions as "Full", "Reduced" and "Off".
Was your new VR aftermarket? I ask because years ago, I got one from Cool Cruisers and right off, it was charging excessively high. I had to adjust it down and then it worked fine. A year or so later when I had the hood off and a tarp over the engine bay, the VR got exposed to rain & rusted up...
12.7 is not enough. Do you also get 12.7 when not running? In other words, not charging at all.
If you can read this diagram, you'll see how it works and where the wires go.
Take note alt components are within the red square. Regulator parts are within the green square.
EDIT: added in the 3...