Keys that don't play? Here's the way to fix. I've kept this as condensed as possible so you can get through it quickly. Similar procedure for cleaning on many other brands.
I have a problem on my XK1, while playing it for 5-10 minutes the sound goes out of tune. It kinda transpose itself down without me touching it. And the tune goes up & down and continues being Fluctuating, that's why i didn't use it anymore. But i want to use it again so hopefully you can help me with that issue. sir.