Going back to basics is a good idea but, you may have a flaw(s) in your game that you cannot feel because you are doing it consistently.
Find a good coach and have him/her watch you bowl and go from there.
Sometimes you can find the flaw(s) yourself and fix them if you do know enough about good execution and mechanics. But, I'd find someone knowledgeable to take a look at what you are doing.
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I'll stone no head pins before their time.
Sr. K will. He gets tapped like that all the time.