After 8 years of flawless operation my keyboard needed a cleanup. Why
i did not simply buy a new keyboard? Because good ergonomic keyboards are
hard to get, and microsoft, logitech and so on are crap (i tried them all).
After i opened the casing it came to me how URGENTLY it needed to be cleaned.
Remove everything.
Im a non-smoker, i dont know why its so yellowish.
First decontaminate the upperside.
Now for each key.
After cleanup and drying... looks good.
This leaves a puzzle that took me 15 minutes to solve.