Is it possible.....

[lerxst88]

well its a trick eddie van halen came up with. i dont know the song but he does it at the beginning of that song where its like "hellloooooo baaaaaaby!" and greg camp from smash mouth does it at the very end of "lets rock"

since youre using electric current to spin the shaft of the drill, the pickups hear that as an electromagnetic disturbance and create a small signal of current down to the amp and you can hear the electric motor of the drill in the amp.

the reason i mention this is rather than install your pickups, wire them up, string up the guitar, close up the electronics, plug in and one doesnt work you can try this as soon as the wiring is done. just hole the drill's motor right above the pickup you want to test.

 

[SonOfIAm]

It may sound odd but check the resistance of the shielding paint in the control cavity of your McCarty. I had a similar issue with the stock pickups in my CE-24 and found that there was quite a bit of resistance between the cavity and the pots. I took the controls out, put couple of strips of 3/4" copper tape linking the holes for the pots and 5-way switch (make sure to overlap the strips and put some solder on the joint) and it made a huge difference!