I'm trying to install a Aguilar OPB-2 and two Bartolini single coils in my MIM jazz bass. Vol., blend, bass/treble. I wired it up as on the diagram, and the blend pot is acting wierd--when I have it set to center, I get nothing--no sound at all. When it's set to either extreme, both pickups are on full. I called Aguilar, and they suggested reversing the wires going to ground and to the vol. pot. Did that, no change. Called Aguilar back, and they suggested a bad (250k) blend pot. Tried the 250k blend pot that came with the fender--same thing. with the blend pot centered, I get no sound at all, on either extreme, l get both pickups. Any ideas?