Quoted from Chitownpinball:So Iron Maiden is Spike 2, right? So these wont work?
https://www.pinballlife.com/index.php?p=product&id=2894
This was the one that may have worked but it's gone:
https://www.pinballlife.com/index.php?p=404
I would call Terry or email him. You are correct the one you linked said it doesn't work, but I found this:
http://costore.com/sternpinball/productenlarged.asp?peid=235&pid=6782968
and this from Flipper Fidelity but it doesn't say specifically which Spike:
https://flipperfidelity.com/sound/pin-vol-exteral-volume-control-for-newer-sterns.html
I hope this helps!
Scott
Pin Stadium
www.pinstadium.com