Well, since you didn't give any information as to how it was drilled before, all I can say is to drill it weaker. Move the pin further from your PAP and maybe higher as well. Look at Ebonite's site to give you some ideas. Their site is very informative. If you tell your proshop the trouble you were having, they should be able to drill it weaker and still fit your game.
BTW, don't worry about plugging and redrilling. I have several balls that have had plug work done. I've shot just fine with all of them.
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Penn State ProudRon Clifton's Bowling Tip Archive