If there is a lot of lost motion throughout the piano, you can shim
both ends until only one or two pneumatics are high. Remember to screw
down the action before you decide if you are satisfied. Sometimes the
shims compress as you tighten things up.
To adjust individual pneumatics it is a little more time consuming.
First of all, set the end pneumatics of each section (bass, tenor and
treble) so that they are as perfect in height as you want. I set them
so that the wippen just barely does not touch the puppet rod. Pull the
action out and support it well.
Next, tape a thin string between the tops of each pair of rods. Pull
the string somewhat tightly so there is no sag. If there are some rods
that are high, turn them down and re-tighten the string. Turn up those
that are low.
Sometimes the adjusting rod is quite snug on the metal rod and careful
force may be needed. Having the action well supported is a good
beginning. If the rods seem tight, hold the metal rod with pliers as
you turn the wood dowel.
There are several tools used for adjusting lost motion. What you don't
want is a broken wood dowel. By the way, work with the pneumatics
facing you. It is much easier than leaning over the stack and trying
to work from above.
The above technique works for me. There are some caveats, though. The
piano action should be in good regulation. If the piano is "bad", the
player action can't improve it, no matter how perfect it is.
If it is necessary to replace hammers, butts or wippens, use quality
parts. You want the bottom end of the wippens to end up in a straight
line and quality parts have closer tolerances than off-the-shelf parts.
It can be tempting to leave lost motion in Aeolian actions, just
because they are hard to adjust. Going through the effort will make
a big result in the ability to play softly and in repetition.