I've got a Fender jazz with two fender single coil jazz bass pickups. There is a metal plate that goes from the bridge pickup to the bridge? What is that? I am thinking of changing the pickups to Sadowsky hum-cancelling pickups, so do they need the metal plate? At least I haven't seen the metal plate in any Sadowsky bass. And as I said, the bass is a Fender jazz, the Jaco Pastorius model. Thanks!