Just an FYI, I once had a flipper that just would not stay put. I could pull on it really hard and think I had it, only for it to move during play little by little.

I went through more than one replacement clasp/bracket thing... bent the crap out of a wrench or two...
Finally it got loose enough for me to realize it was the shaft moving inside the flipper itself... I'd check for it but I could not twist it hard enough to get it to move on my own i guess..