Quoted from Backdoc01:After about a month, the balls I use become dull and lose their luster. I'm looking for some guidance to polish them and return them to a mirrored state. I heard using an ultra sonic cleaner is the best way. Any advice is appreciated.
Really nice balls are ~$1.25
By the time you paid for your time (it's got to be worth something), the electricity, the media, and the Flitz polish, it would simply be cheaper to replace any dull balls.
(and of course, any deeper scratches and nicks would not be touched by the Flitz).