Hi All,
I had some dead keys on my Mono/Poly. Years ago, I tried the CaiKote paint-on stuff and it worked great for a couple of years. After a while, though, some of the keys stopped working again.
Recently, LA Synth Co started selling new key contacts for the Mono/Poly, Polysix, and other synths of that era. I bought a set for the Mono/Poly and installed them. They work great!
If you're interested, you can check out the replacement process here:
http://synthhacker.blogspot.com/2016/02/replacing-key-contacts-on-korg-monopoly.html
It's so fantastic that they've made these pieces available again. I don't know how they're getting them made, but it's a great service.
Chip