In the last 5 months, my scores have seen a decline.  I am throwing the ball practicly the same way, due to video analysis and visits with my coach, and really can't find the problem.  I did however purchase a ball spinner over 5 months ago, and since then I use it to clean my equipment almost every time I bowl, which is about 3 times a week, and re polish, (meaning I sand then polish) or sand every other week or so.  Is this constant spinning of my equipment damaging it at an excessive rate?

I thought about that!!

I agree with baiki. You may be changing the surface(s) of your ball(s) without realizing it. Balls should be cleaned after each use, in general. They need to be repolished or resanded, maybe once every 30-50 games, depending on the wear factor. You could be starting out with a new ball every time you bowl, by sanding or repolishing.

Try to be more even with your use of the spinner; think of it as a tool, not a toy. Yes, I know we all like to "play" (not really) with new tools. Try them on older balls or ones you're not using for leageus or tournaments.

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"When we choose an action,
we also choose the consequences of that action.

If I were you, I'd stick to a good cleaning every week and stop sanding so much.  I only sand my stuff maybe every other month but clean nightly with Simple Green and rubbing alcohol.
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Evolutionary.  Revolutionary.

I always cleaned my equipment on the spinner after every set, then I stopped because I started getting lazy.  My carry and average plummeted.  As soon as I began routine cleaning on the spinner again, my average and carry went back up.  Weird huh?
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*Don't swing it if you can't bring it.*