when you wife tells you how many machines you can have.

I take them out of the wife's purse and look for rust or wear marks.

-Wear, rust, spots of discoloration
-they are magnetized
-they start rolling "strangely" or off-kilt
-it has been a year since they were last changed

If you even ask your self this question just grab new ones.

If you play irregularly, and you don’t get your grubby skin oils all over them, then they should stay good. In that case I’ve heard every thousand plays is good.

I always keep a new one sealed and compare them to what’s in the game and if there is a noticeable difference in haze then it’s time to replace.

Glad none of the poll options apply to me.

Ballbaron.com ninja balls when I need them.

It's not rocket science just look at them. If you see scuffs that don't come off, any rust, or visible pitting they should probably come off.

I have games that probably haven't had the balls changed in years. In climate controlled, dry places they should be ok. I sold a guy a game that he keeps in an enclosed porch. Sold him another game almost a year later and the ball on the old game was rusted and pitted, so replaced it for him.

Just use your eyeballs. As long as they are nice lookin' balls let 'em hang low and lazy.

I guess to each his own...

I think Ive owned 75 or 80 pins and rarely if ever changed the balls unless there was an obvious issue with one like rust or something