Ok, obviously if you are having different things happening when you dont grip it, your still griping sometimes even if you dont realize it. Your thumb hole is probably way too big. White tape, is meant for the front of the thumb hole, the pad side of your thumb, and has a good bit of texture to it. Black tape is meant for the back of the hole, its very slick, almost like plastic. I dont know anything about cork. A lot of people use tape in different ways then they are meant for though, some like white tape in the back, some like black tape in the front, etc etc. I personally suggest you try Ron Cliftons Magic Carpet. It goes in the back of the thumbhole, and its almost like the soft side of velcrow. I think that is the best choice for you. BUT, until then, try using some white tape in the front. To learn to not grip it, make the thumb hole very tight on your thumb with tape, I mean, almost as tight that you need to jam your thumb in. Put a lot of easy slide on your thumb, so you dont hang. If you CANT bend your thumb, you can learn what it feels like to keep it straight. Do that for a game or so, then take some of the tape out, and dont use any easy slide. Try to keep your thumb the same as when the hole was really tight. Then, adjust the tape accordingly.
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....BRUNSWICK!
¡Viva la nación de Brunswick!
Nothing more to be said.
....DEATH BY CHEETOS!!!!