vagfilm I would not get a es120 (or 520) without trying it extensively.
I think your final sentence holds for any DP. Firstly disclosure, my personal ranking of entry DPs when I was shopping was sth like FP30 > ES110 > P125 > PX150 > PX-S1000, but I wasn't really happy with any of them. With the ES110, also because of the bounciness.
Because the es110 was used, I opened it to check if I could improve the cushioning at the key bottom, and found that the key is not stopped at the bottom... In fact the key inever hits bottom! The key is linked to the hammer (if you lift the hammer the key moves down!) and when the hammer hits a top rail it stops the key.
I thought this key action had a damper strip in front of the front edge of each key below, top and bottom for both directions? Do the keys not reach the top one when bottoming out? Could it be raised so that it would, and help damping?
I understand the key and the hammer are not directly linked but rather have a gliding connection?
And because the momentum of the hammer is much higher than the momentum of the key, the hammer bounces back from the top rail felt and that makes the key move up a bit. It is nightmarish to me: you have a combination of hard bottoming that is also bouncy.
I think the issue of the hammer stopping abruptly is present in all key actions, and there are others known to get clunky over a relatively short time, eg Casio PX.
Btw, the large bounce on key return is also caused by the hammer. When the hammer crash-lands in the bottom felt it will bounce a couple of times until it stops. All those bounces make the key also move along.
Sure. I'd just comment that there are many actions that bounce like this a little bit but one notices it only when paying special attention or using a high-speed camera. And in particular, I've seen two models with Kawai RHIII side by side, one of which was annoyingly bouncy on key return, and the other was quite nice (a then fresh CN39).
And you can't do anything because if you add foam to soften the hammer landing, it alters the resting position of the hammer. If the hammer resting position is now higher, it causes the key to lower down a couple of millimeters.
I'm not sure if indeed nothing can be done. I guess the thickness shouldn't be altered, but maybe the material and its properties matter. The Kawai tribe never wanted to make any conclusive statement regarding this, but release notes of some recent models do mention minor modifications of the key action. Have you asked Kawai service for replacement damping strips, possibly improved ones? Or maybe one should look for an appropriate replacement made from a more durable material. And how about re-lubrication (the Kawai seem to use two types of grease here)?