A few years ago, I didn't use inserts or slugs. My fingers and thumb would more often than not be sore after a night of bowling. I also had to deal with the uncomfortable feel of trying to throw after my hand swells up. I thought of the possibilty that I didn't have the ball fitted properly, so I had it done again.
The shop suggested to try grips initially, along with trying to not hold the ball with the jaws of life. The difference was night and day. The thumb slugs came not too long after that. Even my spare ball(which isn't even a true spare ball) has grips and a slug. I can't even imagine throwing a ball without it.
Since you have a new driller, why don't you try it again? Take a ball(if you have one)that you don't use anymore, and see what happens.
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Behold the bold soldier, control the globe slowly
Proceed to blows, swinging swords like Shinobi-Triumph, Wu Tang Clan
High game-300
High series-796
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