Quoted from Tranquilize:scratched balls killing playfields
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My friend bought a mata hari that did not have the rubber on the launch pin. The pin was peened over from years of use. The ball was hammered. The playfield was scoured down to the wood in many places.
A used ball is probably detrimental to a playfield but the degree of damage is dictated by how bad the ball is, how much the machine is played and what playfield it is on.
No matter how much use my games see, I change the balls each year. Even a coating of oxidation is abrasive. YMMV
