Thanks everyone, this is very helpful. The hum canceller seems to do fine where it is. Thanks for the Jazz Bass pickup schematic, I'll use it for some measurements. I think the neck pup is in the Pbass position, which is what I wanted when I had it moved back.
JimmyJ: I think it's a dang cool bass! I have 5 basses, and I will never get rid of this one and my '63 Jbass. They pretty much do it all!