Neck Pick up Loose in Rick 4003

[Minky]

Any help on this would be fantastic. The bass is a 2009 4003 and has hardly been played.

I've just recently encountered the following problem that maybe you could advise on?

The black rectangular metal part of the pickup that is contained in the housing unit has become loose and can be moved around horizontally within the confines at the top of the pickup unit. There’s no effect on the sound. The pickup itself is solid but you can hear a rattle when you play the bass i.e. the loose bit rattling.

I'm more than comfortable trying to fix it myself if put in the right direction. Obviously, it would involve removing the scratch plate and pots which is no prob but any advice on what it might be would be really appreciated.