Woodkeys Kawafanboi, are you able to provide some links or other pointers on the detail of to how to carry out this regulation? It would be much appreciated. I do agree that Kawai should provide a thorough, step by step procedure for owners that would help them carry out the regulation themselves to produce optimal results.
IF you care about calibration stability, my ONLY recommendation is Don't buy one of these. the DRIFT NEVER STOPS. it's perpetual. You have to be a very dedicated enthusiast and frankly ENJOY regulating the action. i enjoy regulating my own piano, but if i could wave a magic wand and never have to do it again, i would, i'm crazy but not that crazy.
As for anyone who already owns one, the adjustable key geometry which affects drift is the key height, key dip, and capstan.
There are other geometry problems which you can't adjust, such as the wood twisting differently on different keys, or the position of the pivot hole being slightly forward / backwards, they angle the pivot pin, sometimes by alot to account for this, which means that key is not rocking the same angle as the other.
In the latest action iteration, they've removed the capstan screw, but have a rubber pad sort of thing now this means a slightly reduced maneuverability on your end relative to the older gf. I don't know for certain, but it may still be possible to put shims under that back cap, or adding some tape to the top plastic.
key height, is adjusting the height under the pivot pin
key dip, is adjusting the front punchings
KEEP IN MIND, you will never ever ever get it perfectly even, the way it's designed it's virtually impossible.
Refer to this page for more info on people who have done it, https://forum.modartt.com/viewtopic.php?id=6886
there is also a software method being worked on in that thread which can smooth out the output some, but this is only through midi-capture, it won't help the onboard sound engine if that's what you play, it's again not perfect, the drift will never stop.
finally, lubrication could need touch up every year or two.
i am not entirely anti-drift, but i think they really should warn buyers, because it may not be what they signed up for on a digital.