It's very hard to read those numbers, but I'll do my best, also keep in mind that I'm no expert, so my suggestion isn't guaranteed to work. Okay, now, from what I can see in the diagram, it looks like when the switch is in position 4 it connects terminals 4,8, and 12. Terminal 4 connects everything to the bridge. I would try disconnecting that light green wire from terminal 4. That should isolate the neck pickup.