I recently had a similar situation with my SR5. One of the wires coming off one of the coils needed to be re-soldered. I was able to diagnose the issue using the screwdriver on pole piece technique mentioned above. Until the fix I was basically in single coil mode, regardless of selector switch position.
However, my bass is almost 30 years old. I can't imagine this being a problem with a new one, especially if the single coil option is no more. If yours is used and made before the change to the switch function then it might be worth looking into. If new I'd let Ernie Ball take care of it to make sure the electrical guts are all functioning properly.
However, my bass is almost 30 years old. I can't imagine this being a problem with a new one, especially if the single coil option is no more. If yours is used and made before the change to the switch function then it might be worth looking into. If new I'd let Ernie Ball take care of it to make sure the electrical guts are all functioning properly.