Hello. I acquired a 80s Washburn A-15V sometime ago and it's PU selector had broken, so I replaced it and now have been rewiring it. So I wired the grounds, the input jack, everything that's supposed to be wired. However, there was one blue wire left soldered into the middle lug of the volume pot. It had been soldered somewhere on the old pickup selector before I snapped it off (and of course didn't mark from where).

I'm having trouble trying to find the purpose of that extra blue wire. Since the input is already soldered in the middle lug aswell, what's the extra wire for and where I should solder it on the PU selector?