Yep, what Simon said. Disconnect the white and keep the tip insulated.
Mixing different brands of pickup can often result in out of phase combos. You can’t reverse the neck pickup due to the way it’s made, so the Bridge’s red (+) and black (-) are your reverse option. The Bridge pup’s bare braid should stay connected to ground and once the white is disconnected and insulated test the middle position of the switch. If it still sounds out of phase then just swap the red and black connections.
After removing the White wire from ground, and totally grounding the braided wire to the back of the volume pot seems to have corrected the issue.
That, and my output (Green) wire was not properly soldered.
I think those three issues once resolved, give me more out of the MM HB, balanced better with the SC in the middle postion.
Thanks guys!
OH! And raising the MM HB up from where it was, that never occurred to me, totally over looked the distance from pup to strings, even though I must have read about it several times. Seems that resolved my volume issues, Duh! I just over looked it.