ok ... i got a better look at the Volume pot: both yellow wires are connected to the same tang ?so: either one to the Earth for the Jack and the other to bridge as the earth - which in this case im assuming anywhere on the brass mouniting plate will suffice as a location?
Again .... a LOT of thanks ..... this poor project has been a real tooth puller .... hounded by issues of one sort or another ... and this was almost the "bridge too far" ....