Well I went into to practice with my coach today.  We had a really good session I feel, and really loosened up my swing to get my ball speed up.  We also worked on a few timing issues.  After working with my coach for about 45 minutes i had to go to work.  After work about 7 hours later i decided to toss a few more for about a half hour to keep working on what he taught me.  After the first few warmup balls i started to hear a cluncking noise going down the lane.  I looked at my track and it was clipping the thumb hole.  I normally have a lower track my PAP is 4 1/2 by 1/4.  THe only ball the would track over my thumb is my urethane ball that i like to practice with, and my plastic.  The rest of my reactives the track was higher by a great deal but not enough to roll over the thumb.  
I am a tweener i throw the ball about 16 MPH and have about 275 RPMs.  The urethane ball the i was tracking over the thumb looked like this.
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What is the diagnosis guys???

Edited on 3/9/2007 0:02 AM

I had the same issue... I wouldn't take my advice to heart but what I did was change my wrist position a little bit to where my index finger was pointing towards the pins and was under the ball.  My issue was that my wirst position was causing me to come up the back of the ball too much and I Was tracking extemely high and over the thumb.  Like I said I'm the last person to take advice from but it worked for me.

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