There are many games with this layout. Earlier games had one rubber, but later games specify 2 rubbers in the manual. I assume Gottlieb learned there were problems and fixed it on their next release. That said, if you don't have problems, and it's home use, I wouldn't worry about it much

Double them. It'll keep the ball from getting trapped, and more importantly, it will help save the plastic light shield from breaking.

I found 2 caused the ball to bounce on Jumping Jack and Sherrif. I stuck with 1.
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I have double rings on my Solar City. In a home use 1 ring should do the job. On route, when a ball gets stuck, the game is not making money. Double rings on large spaces between posts, with the drop targets all down, sometimes in the center of the older rubbers the ball can catch up on the drop target hole and wedge under the playfield plastic.