[ChristianRock]

It isn't worth fixing! Too much got damaged by heat and wrong soldering with the flame of the butan-gas soldering-iron!


Not really. I have answered that one in detail HERE but I cannot agree with:

Having repaired quite a few of both of them, I would say, that without instructions finding out about the hidden screws of the K-S1 is pretty difficult.
But we have those instructions and in my experience the difficulty-level is almost on the same level.

I did follow your instructions and found them extremely helpful. I see no issues with them at all. But I do think the chassis of the K-S1 is a lot thinner, easier to break the little plastic joints, and so it must be handled quite a bit more carefully than the K-S2, which you basically unscrew and take apart. That is all.