Bernt,  "Clair de Lune" is a tough test.  I use it after installing
PianoDisc systems, to test the setup to seek perfection.

A couple of possible suggestions for you: Is the soft pedal on when
the chords are playing?  The soft pedal introduces lost motion and
more power must be used, to play quietly.  Is the piano action heavy?
Is there friction in the piano action?  Has it been well regulated?

Run the test roll and turn up the minimum level.  I do this with the
switch set at Soft, which turns on the soft pedal.  You may need to
play around with the minimum setting, turning it up, and adjusting the
soft pedal throw, then turning it down (limiting effect).  Get the
owner's okay of satisfaction.

Good luck,
Jeff Davis - in Seattle, where spring is on its way!