Hi, I have an old Iby J (my first bass) that was gathering dust, so thought I'd give her some love. Changed out the neck pup for a dirty great big humbucker, got some CTS pots, a Sprague orange cap and a couple of micro switches and set to work. What I have is the neck humbucker going through an on/on DPDT for series/parallel switching and the original bridge J going through an on/off/on DPDT for polarity(phase) switching. The output of each switch goes to it's own volume pot then both to the tone and out to the jack as normal. Everything works perfectly apart from when the humbucker is in parallel (I think), the J volume pot acts a master volume (regardless of the polarity/phase switch) but not when it is in the series position. So if the J volume pot is down, I can't hear the humbucker!!! I don't understand what is going on as this doesn't happen when the humbucker switch is in the other position. I would really appreciate any thoughts or ideas or the help of someone who understand this stuff!! Kev.