The Last Bass Outpost

I just recently emailed Bob Daisley who played an EB3 on Ozzy Osbourne's Blizzard Of Ozz album.  He says that his EB3 had a toggle switch instead of the varitone and that it was stock, no modifications.  Does anyone know on here when these would have been produced?  Pictures of the bass are on his website and the neck pickup is right up against the fingerboard and it's not a slothead so it must be pre-1970.  Would this have had the tonechoke circuitry and if so how would have it affected the sound?  Unfortunately, he no longer has this bass anymore.

I did a Google search and found a modification that is supposed to solve this problem.  Apparently it involves just switching a couple of wires on both volume pots.  Not sure if I want to mess with this as I primarily use just the neck pickup but I'm attaching a schematic with the mod.  This is a much easier schematic to read, BTW!

Several years ago I had a local music store wire in a Dimarzio Model One pickup.  I decided this year to put the original pickup back in which I wired myself.  I've never really used that position on the varitone before (always used position 1, neck pickup only) so this is the first time I noticed this before.  I've attached a picture on the innards if that helps at all.  Thanks for the welcome, glad I discovered this site!

Just want to confirm a response I got on another forum.  Going through the varitone control on my 1970 Gibson EB3 it seems like there's a problem in the third (both pickups on) position. In order for both pickups to work I have to have both volume controls all the way up. If I turn either down, it turns off both pickups. Shouldn't each volume control affect its own pickup rather than both acting as a master volume? The other settings all appear to work correctly.