It would seem that the threads in the case are stripped, either during manufacture, or you screwed it in too tight.
What would *I* do? Just a touch of properly mixed JB Weld
and glue that puppy in. Screw it in and let harden for a few hours.
Why JB Weld? Because I already have some laying around, and it insanely strong.
That's what *I* would do, anyway.