Odd problem with 51 P-Bass reissue-no sound, except when...

[mjau]

I was playing my 51 reissue last night, and all of sudden the sound went from full and loud to barely there. I've been checking it out this morning, and what I've found is that if I touch the E or G string to the pickup magnet and hold it there, I get a full signal coming out of the bass when I thump the other strings, but when I'm not touching the string to the magnet, there's no sound. I've checked solder points and they all look ok, so what could it be?

[rodabod]

Possibly one end of the pickup wires has lifted away from ground.

[suppositron]

Yeah you can't just rely on the look of the solder joints. They can look ok but there can be a break in a wire somewhere. Could even be one of your volume pots.

[mjau]

Cool, thanks for the suggestions. I went ahead and touched up all the solder points on the pickup and at the volume and tone pots, and now I can't get any sound. Obviously, I messed something up. Maybe it's time I just upgrade the pickup, anyway.

[A.David.MacKinnon]

It's a ground wire issue.
I had the same problem with a baritone guitar.