I’m rebuilding flippers on some system 11 games, and as I suspect is the case for basically any machine of this age, I’m finding a mix of original coils and replacements.

In cases where the replacement is not the same spec as what’s called for in the manual, I am replacing the coil with the correct spec one (11629 vs 11630 for example).

Other than that - if the flipper is working well otherwise, is it a good idea or a waste of money to replace the coils? If a coil is 30 years old but still working...is there any value in replacing it (does it degrade over time) or, is the performance of a coil more or less binary...it works, or it doesn’t (open or short)?

Not replacing them is obviously my preference...it’s less about the $12 (although I’m very happy to not spend it) and more about taking perfectly good parts out of service for no reason.

Thanks.