Thanks, DVM - yes, that's the wiring diagram, and it is the bridge specific control. With the old pot, when I shorted the pup input/output lugs, I would get full volume on the pup with a lot of hum, which got less if I touched the bridge. With this pot in, if I short those lugs I get the hum, but not the full volume (this was an accidental discovery which I mention in case it proves diagnostic in any way). The other controls work fine with the neck pup - with the selector switch I always get the neck pup in both the rhythm and the combined position and I get the bridge, too, in combined and lead position when the pot is working. Master volume and both tone pots also working as normal.