Scott,
1. 9/16" is a LOT of reverse pitch. I hope that's what you REALLY need. WHen I went to 3/8" reverse, I found I had to keep the thumb hole perfectly sized to match my thumb's shrinking and swelling during sets. If I did not constantly add and remove tape, I would drop or knuckle the ball (to prevent dropping). When I went down to 1/8" reverse, I add and remove tape much less often.
2. In about 2 of your replies above, you stated you were good for a long while then it stuck again. If that's true, then maybe you just need some strong alcohol to clean your thumb and the hole in the latter stages of your bowling, be it 3 games or 5 games. Our strongest drug-store or supermarket alcohol is 91%. That's fairly strong and will clean oils and sweat off your tthumb and most dirt from your thumb hole.
Carrying a 4 oz (125-150 ml) plastic bottle in your bowling bag is easy; I carry one. carry thin cotton towel to clean thumb hole and thumb.
Last question: are you sure your thumb hole fits properly? so you can't knuckle (bend) your thumb at all?
If your thumb shrinks as you bowl, adjust the thumb hole at the start of bowling with white (sticky, rough surface) tape or the black kind (very smooth). Then add tape as your thumb shrinks during bowling. YOu have to be VERY aware of how your thumb fits when you start: it should be ALMOST snug. WHen it gets too easy to put your thumb in, it's probably shrunken and you need to add more tape to the hole.
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"Those who do not remember history are doomed to repeat it."