Originally Posted by SGD Lutherie
On a split coil humbucker, the second coil cannot have it's start at ground, since it's connected to the finish lead of the first coil. That's why you need the poles grounded.
It's very tricky to get a good electrical connection to alnico rod magnets. It's typically done with copper foil tape with conductive adhesive. And even then, it doesn't always stick well.
If you are getting the hum on the E-A string side, which is where you might rest your thumb, you can fix that by reversing the polarity of both pickups. That way the start lead will be connected to ground.
Obviously you don't want to take the pickups apart, so I'd contact Aguilar.
Thanks; I think after some careful thought I actually understood that. If I've got it right, then, this is just an annoyance with no effects beyond the noise when I touch the affected polepieces---it shouldn't be affecting the signal of the pickup in any other ways?
Further experimentation (cross-connecting polepieces to one another) reveals that the first (E-A) coil of the neck pickup and the second (D-G) coil of the bridge are ungrounded; I can make the issue go away by connecting them to their grounded partners, so I guess I could fix it with an attractive piece of conductive tape across the middle of each pickup. But I'm not sure I see that it's worth fixing---this isn't something that's going to come up while I'm playing.
Edit: But wait---if the whole coil, not just one pole, is ungrounded, why does the meter show continuity on the other three poles of that coil? But if the other poles are grounded, why doesn't connecting the "bad" pole to one of the ones on the same coil fix the problem? Am I overthinking this and I should just shut up and play my bass?