If it slips off, and you try to put it back on without cleaning the inside of the diverter, well, that's just like not cleaning the muffler port. So, make sure you clean both the muffler port as well as the inside of the diverter before putting it back on.

As I said earlier, I have them on my planes and have never had one fall off.

I've broken one or two from un-natural causes.. [:@] but I've never had one fall off.

CGr.