My opinion-
Replace the ball that is cracking- if its under a year old, ball company should warranty it, unless its the drillers fault (most cases b/c holes not beveled, or drilled to close to the pin, etc...)
The balls that a 200 + games old, try either rejuvenating or reviving them at your local pro shop (machine emits a low heat to a rotating ball under controlled conditions) and getting a surface tune-up and the balls should last a few years anyway (until the surface diameter becomes too small)
If your local proshop doesn't offer that service- you could ship them to me and I'll do it...lol
You can also try the bucket method
5 gal. bucket + luke warm water- change water and wipe off ball every 15 mins until you notice no oil coming out of the balls cover..
"if it ain't broke, why fix it" adage comes to mind, if your happy thats all that matters.
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James McCarter
Co-Owner/Operator
The Bowlers Solution INC
www.bowlerssolution.com