I've been using a mixture of 75% Simple Green to 25% water on duller balls or balls I want to keep dull and about 50-50 on polished balls. I primarily use it to get off the dirt and oil on the ball but it doesn't take the belt marks or scuffs off the ball. For that I use Neo-Tac's Hook-It, which is a great cleaner btw, a little expensive but well worth it. That take the belt marks off like nothing.
If I trade for a new ball or notice a big drop in performance, I soak the ball in hot water with Simple Green or Dawn, scrub it with the backside of the sponge while soaking, take it out and dry it off post haste. Then I take a generous amount of Neo-Tac's Hook-It and really scrub the ball on a rag. And the ball, had it not had any nicks or scratches, would look brand in new.
--------------------
Bully Your Competition