The bass shutting off completely when one pot is turned all the way down while one is still up is not due to the pots being bad.
It's because of how they are wired. Many older dual pick up guitars were factory wired this way. Forget the exact term, but I seem to remember it being called "50's wiring".
Easy fix by swapping around a couple wires.
That's what Gretsch told me, too, when I called. I'm leaving it as-is because I don't wan to modify this bass, at all.
TY for the info