Gads, the grey wire from my 77 4001 bridge pup came loose. The black one is soldered to the back of the bass volume, from the photos on line I can't tell where this goes. I know this is a mess, I bought it this way and will be buying a new harness after the new year. My finger is holding the wire and the ground(black) that is right on my finger is from the bridge pup. Here is the photo.