dropping or hanging in thumb

Question
This is regarding fitting, my personal background is 25 plus years of ball drilling and 30 years competitive bowling, I'm IBPSIA level 1 and also a silver USBC coach. I have been having trouble with my release which started in 2008, I began to hang up in my thumb hole, not every shot but over a couple of years became about every 3rd or 4th shot. at that time my span was 4 3/8 ring and 4 5/16 middle with my thumb pitch for the last 20 years had been 1/4 reverse & lateral is 0. I have experimented with all kinds of angle changes from 1/2 reverse to 1/8 forward and even tried laterals 1/4 left and 1/4 right. Even though I'm unhappy with the release I have continued to excel locally and even shot a number of honor scores (god bless easy house shots). At bowl expo talked to the guys at Kegel and was refit and they suggested my new specs 4 5/16 ring and 4 7/32 middle. due to damage of dropping balls in the middle of my swing my ring has 1" reverse and standard 7/16 lateral left, middle is 1/4 reverse and 5/16 right (yep lefty here), the new thumb is 7/16 forward. new problem ball is falling off my hand but my thumb hole is so tight that its hard to insert all the way. I have silver tape in pad of thumb for grip and enough tape in back (knuckle side) that if i use rosin or hand conditioner I can't get my thumb in all the way. If I use less tape to allow thumb to be in all the way, rosin or not I drop the ball during my swing. I need something to make this sport I love fun and enjoyable.

Answer
Steve,
Let me get some additional info: How stiff/flexible is your hand? (Hold the hand in front of you, eye level, observe the angle of thumb and index finger, what is it?. Can you move the thumb with your right hand and gain more angle? How much?) Does the hand stay dry, is it moist, is it clammy, when you bowl? How long are fingers and thumb? Do you have a tight web between thumb and index finger or is the skin between the base of the thumb/hand loose?

What is the rest of your fit? Hole sizes, grips, no grips, thumb grip/slug/Interchangeable? Picture of fit sheet maybe?

Is the thumb hole round or do you oval the hole? Is the knuckle fairly broad, possibly significantly bigger than the base of the thumb? If you work the thumb hole what kind of tools do you use? Do you get all your equipment fitting perfectly? What is the amount of span difference IF the spans are not all exactly the same?

Let me know more about your fit and game, a video would be great, or pictures of your hand and hand in the ball. Thanks for the question, look forward to hearing back from you.