I have what appears to be a '95 vintage Sterling Bass (based on the serial #), single pickup version. When the bass is rotated from vertical to horizontal (as if it where laying flat), it sounds like something is loose inside the pickup, like maybe one of the poles is moving. It sounds like a marble in a spraypaint can. I haven't removed the pickup yet to check it out but thought I would write to see if anybody else has experience this. They guy I bought it from said it dropped on stage once and it has the rash to prove that. I have removed the pickguard and checked the battery compartment and the noise definitely is coming from inside the pick up.