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

Agreed! It sounds like the rubbers are starting to deteriorate.

Where are you ordering new balls from?

Did you clean the oil off them before putting them in the game?

And did you clean off the oil from each ball with a degreaser?

I'm not sure if you're aware, but pinballs are typically coated with an oil to help prevent rusting while in storage.

When installing fresh balls, I also take the extra measure to wax them, but not everyone does.

THey are Ninja balls dammit! Reputable ones!

Sounds like the game needs to be shopped as well. Replace the rubber kit. Clean the metal parts (ball trough, under the apron etc) and mini playfield area. Dirt/Grime underneath will find it's way to the top.

It's a rookie mistake, but you're only a rookie after doing it one time since you will remember to clean them every time

In all seriousness, I am sure it happens to tons of guys in this hobby. But usually only once.

Goodluck mate