Jeffy, If yer balls aren't black you're not pushing hard enough.

The Powerball cleans up nicely with soap and water. See pic attached. It takes a couple of washes though. Wear seems imperceptible so my guess is that it will outlive the wheels. I used Mothers aluminium wheel cleaner as the polish.
Definitely a finger saver and works faster than I could have done by hand.
Dr. Spock, yes, that drill has been around the block. Still have the original box and paperwork for it.
Railton