As far as I can tell, back in the 1980's all Bally Centaurs
had standard balls. Take into consideration that you are using
laser cut plastic and not the original steel rule die cut plastic.
variations will a cure from recreating one set of plastic from the other.
When the games were in the arcades that I worked at the
ball in the queen's chamber never popped out.
Has far as stuck balls in inline drop target assemblies,
Electra was notorious for that problem.