Quoted from docdeath:tuna_delight Is overheating of flipper coils a common problem? I have two Stern & one JJP games and haven't notice over heating. This is the first time I've herd of this problem. Maybe it's because my games do not have extended, greater than one hour, play. My son has 23 pinball machines and has also not notice a problem with over heating coils in any of his games. I've been on Pinside for 10+yrs. and this is the first I've heard of this problem.
The coils aren't overheating. That is not the issue. As the coils heat up they lose their 'POP'. You will notice this on most modern games especially when having a long game, long multiballs etc.. where the flippers are getting a lot of use and not much time to cool off.
Typically when this happens you think, 'is it just me or are these flippers not as powerful as they were earlier?' If you have ever said or thought this you have probably been experiencing flipper fade.
If you have never noticed it, it probably won't ever bother you. If you have noticed it, you will want to do something about it.
I don't know if Pinmonk coined the term flipper fade or not (maybe) but he seems to be the first person to actually do something about it. I have seen passive radiators used before to cool off coils but this is the first active cooling solution that I am aware of. I can't wait to get these on my JJPs.