A ball must be a specific size. A resurface will take a very small amount of the ball away, but unless you get really wild in doing it, you can resurface a ball more times than most people will keep a ball.
Dulling it, then , as long as your coach suggested it, would be your next step. I would say, know your pro shop guys, if that's where you are going to have it done. My wife had a ball resurfaced a few years back, ( before I met her) and they left it on to long or didn't use water, something happened, they took out the serial numbers. Granted it is an Ebonite and they don't stamp the numbers as deep as some, but we had a heck of a time finding numbers and restamping them to keep her ball legal for tourneys.
If you are going to do it yourself, then you will know when you are getting close and not go to deep into the ball. It sounds like you are only going to make a mine cover adjustment, so there shouldn't be a big problem.
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AZ Guy aka: R & L Bowlers Pro
rlbowlerspro@cox.net
www.rlbowlerspro.comSleep is over rated.