I've been useing simple green for years with good results.I spray a 50/50 mix of S.G. and water on the ball,let it soak in a few minutes,spray it again and turn on the spinner and clean with a new towel.I follow up by spraying on some water on the ball and spin while drying with the towel.the ball ends up squeaky clean.S.G. won't clean belt marks though.
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The harder I try the harder they fall