In my partscaster tele I changed the neck pickup from a single coil to a humbucker (SD Antiquity). Now there is a loud clacking sound when I tap with a pick or my finger on the cover of the humbucker or even on the pickguard. I don't recall ever having this issue with a humbucker before. I've tested to make sure everything that should be grounded is grounded. I shielded the control cavity and both pickup cavities. Any ideas on what the problem might be. Or do I need to learn to live with it?