Might want to try the bowling thumb sock......It has fixed all my thumb fit issues I have had in the past. I use the seamless open tip version and I love it!! If you ever have trouble getting out clean then I strongly recommend it. The only issue with it is that is you don't have the thumb tight enough it will fall off in the backswing. They have also added a less slick material to the fold now that will fit the bill if the lycra is too slick for your liking. I just use 3/4" black tape in the back side of my thumb slug (turbo switch-grip) and I never had an issue.