I have A 2004 mim Zone Bass. And when the p pickup is on(pan pot) Ir makes a sizzling sound. When the J or neck pick up is on it is dead quiet. And if I touch the hold down screw it gets way louder. On the other hand if I touch the jack or the bridge it gets quiet. I have run a seperate ground from the bridge to the pickup and it gets worse. I have no Idea what is going on with this thing. Maybe I have a bad pickup. I have also wrapped the coils of the pick up with insulating tape and put heat shrink tube on the mounting screws and it makes no difference.