J-retro noise/problems

[theschnitt]

I have a Skyline JO5 with a J-retro. I got it with a Nordstrand P/J setup, and also the original Fralin single coils. For kicks I swapped back to the single coils. No problem. Now I went back to the P/J and major problems: major hum when I make finger contact with the pole pieces, and it pops upon touching the string. So, I swapped the SC's back in, but the symptoms are the same.

The guy who did all the work swears up and down that everything internal is grounded. He also is sure that there is nothing else he can do.

Any ideas? Anyone have a similar problem? I will try the ol' tape/fingernail polish to cover the pole pieces, but I can't help but think that whatever has caused this issue can be reversed. I'm baffled. This is my main bass, and I am totally crushed that it's in this condition.

Thanks:
Pete in Tucson