Quoted from metallik:Most Bally/WMS games used dual-wound coils which don't seem to suffer heat issues as much as the newer duty-cycled coils. They would fade, but not to the extent shots weren't makeable.
If 100/flipper is too much, go to the computer store and get cheap 12v fans, cut some metal strips to mount them with. Won't look as nice but works the same.
Spooky and JJP still use B/W era dual wound coils (Medieval Madness, jjGnR, and Spooky pre-R&M all use dual-wound FL-11629s, for example) and have heat issues, even while holding. Whatever magic Stern is using on Spike to have the coil temps not rise more than a degree or two when held for up to 30 minutes needs to be adopted by Spooky/JJP. It's the most surprising thing I've found in the testing so far and a definite change from Stern's Whitestar/SAM system which would blow a transistor if you tried holding that long. It also allows Spike Tibetan Breeze kits to just use the "standard" quiet fan and be cooled well.
You can see holds still increasing temps on jjGnR (FL-15411 dual wound on the left flipper, FL-11629 dual wound on the right) on Karl's stream from a couple days ago because he had live temp gauges on the coils as he played the stream out. Even with fans cooling the coils, they're still creeping up when he's trap shooting a lot from the 55 minute mark for about 15 minutes:
https://www.twitch.tv/videos/900190993
Without cooling that kind of play is how the flippers zoom to 180-219F quickly and play like noodles.