Quoted from Craigd:acdc damaging my balls
Ouch! 
It’s probably rubber residue from the black rubber on the machine.
If it’s original, it probably needs to be replaced.
It’ll get stuck to the balls, and leave muck everywhere.
Post up a picture of the balls - but that’s probably what it is.
You can clean the balls with Autosol (from Repco over there, probably) but unless you replace the rubber, it’ll happen again.
I recommend silicone to replace the rubber. Easier to clean, and you won’t have these problems again.
rd
West Chester, PA
