Mike, I've tried a couple searches, I know we have threads on safties on here.
I found posts about stickin and stuck safties, and I know I've read and heard about safties slippin and not stayin put.
What I recommend but not from experience, take it apart and make sure the pieces are all in place properly.
You'll want to find a topic on here about removing the safety for recommend advice and ideas to get the thing apart and put back together properly. The ball and detent plate are gonna be important.
I dont know if that will lead you to a source of the problem or not. Let us know Mike!