Shotgun mic curiosity
 

Ive got a shotgun mic that started acting up, sounds like a loose wire. I managed to get it apart before busting something. The short tube with XLR connector has the gnd rivited to the centre of a tube inside that one that then goes up into the long tube that houses the electronics and inserts. The other 2 xlr pins run wires up the outside of this inner tube to the long tube and onto the circuit board. I found thatvthe gnd wire is open circuit between xlr pin and rivet on top of short tube. How would that come adrift? I cant get short tube undone. Any special way? Anyonehad same problem?

Thanks