I am sorry to hear that you had a rough night of bowling! The most common cause for the problem is timing. Lots of people change their hand position and speed for spare shots. By doing this, it throws off their timing just enough to create a push or pull response. If you are tugging the ball left, that means that your feet are beating the ball to the foul line. When this happens again, focus on slowing your feet down just a touch, and it should fix it. Best of luck in the future!
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