Alternator - regulator mismatch?

Mattax said
This is likely a point of resistance.
View attachment 1715657007

Clean that, recrimp and/or solder.
Insulate it!
If there is not enough wire to take apart and redo with heat shrink tubing, use liquid electric tape with or without a wrap of electric tape.
Route the wire up when reinstalling so there is less stress on the wire where it joins the terminal.
View attachment 1715657011

Actually resistance in the charge line does not cause regulator / voltage problems. In fact as long as no accessories are sourced from the charge line, the only thing that causes--within reason--is heating up the wire. Of course it can become a problem in just that way.