I've listed the symptoms so hopefully we can figure it out before I pull it all out (hopefully I can still get the Bridge Volume out by itself).

1) Selector on both pickups, both humbucking. Volume max on bridge volume greatly reduces volume/kills the sound, a touch off from max and it's all good: nice and loud
2) Selector on bridge, both humbucking. The bridge pickup doesn't give much volume (or maybe any?).
3) Selector on bridge, bridge push pull "up". The bridge gives perfect volume.
4) Neck volume seems to act as a global volume control when the pickup selector is on both pickups (LP wiring???)

I guess this means that there is a short on either one of the jumpers on the Bridge Volume, or it's either the white or white striped wire?

Or am I misunderstanding how to get around the comprimise you mentioned?