Update
My tech cracked her open a almost fainted when he saw the horrible wiring job inside the control cavity. I also was shocked how sloppy wiring was done. There seemed to be more wires then the space shuttle! And mind you this bass is stock, never modified.
Now compared to my Sadowsky, the wiring on that bass is a work of art. The wiring is nicely bundled together and harnessed. But in the G&L it looks like a free for all.
Well my tech is not too confident working on this puppy, he admitted it is over his head trying to figure it out.
So we might enlist the help of Kevin Kaufman (yep, Jaco's old tech) to take a look see. He is good with electronics, installed a Sadowsky preamp into a Fender Jazz I had. So.......stay tuned!
A mess is no surprise on a G&L. One of my L2500s was like that. The answer in my case was to simply rip all the wiring out down to the switches and pots and rewire it with teflon wire. Only the pickup wires are still melty plastic.
In your case that would be even more important because you intend to change the controls and operation. So first work up the wiring diagram you want to try and then after stripping down to pots a switches wire from there.
I would point out, however that vol/vol setups in essence short the pickups for volume control and that changes the loading impedance and could change the tone. While I've heard a lot of people talk about doing this, I've never seen one that actually did it, so I can't say what the result is for sure. So if you do it, be sure to report back to us on how it works out!
