John Kiszla has sent out a request for parts to replace those missing
from his newly acquired Chickering.  I hope he gets them soon.  His
request shows once again the practice among certain rebuilders that
I disdain.  Those missing parts were removed by a prior rebuilder who
decided they were more trouble than they were worth.  That is certainly
not my opinion about those parts.

Here is what he missing and I will follow that list with my opinion of
why they should be retained by all rebuilders.

 equalizer (2)
 automatic expression cut-out
 loud pedal compensator (2).

The Ampico equalizer(s) are installed in each stack feed line, bass
and treble.  These equalizers are needed to achieve fine regulation
in extremely quiet music passages.  Their function is to act as tiny
reservoirs to dampen transients when the vacuum level is very low.
They compensate for slight dips in the vacuum level that occur as
valves respond to openings in the music roll.

If the equalizers are removed, the minimum vacuum cannot be set to the
lowest possible setting, and thus the quiet playing is compromised.  It
takes less than one hour of labor to completely recover, refinish, and
reinstall these pneumatics.  The cloth couldn't cost more than $5.00.

The Ampico expression cut-out is a bit more trouble to rebuild than the
equalizers.  Its purpose is really two-fold.  As its name implies, it
is the device that disables the Ampico expression.  For most of us,
that is of little value as we never want to disable the expression.
Still, that is useful at times.

Its most important function is as a lint trap.  The brass filter
screens within the cut-out protect all the expression valve bleeds
against clogging.  This function is huge.  Without it, any bleed in
the expression device that becomes clogged is extremely difficult to
access.  Removing and replacing the lock and cancel valves to clean
clogged bleeds will soon lead to other problems.  Those other problems
involve fragile gaskets, wood screw holes stripping out, and difficult
accessibility.  The Ampico Expression Device should never be discarded.
When rebuilt, removal of the pneumatic cloth will reveal the brass lint
trap screens.  There is always lots of lint inside.

More controversial than the two previous devices is the 1927
improvement called "loud pedal compensators".  These tiny (one inch
square) pneumatics reside on top of the spring pneumatics.  Vacuum is
supplied to these compensators anytime the sustain pedal valve is
activated.  Their purpose is apply a small amount of downward force on
the spring pneumatic, thus making the stack vacuum drop slightly.  This
action compensates for the weight of the dampers.

Like the equalizers above, the presence of these compensators improves
the softest level of playing.  By properly adjusting these devices,
a velvety smooth level of soft playing can be achieved.  Once this
concept was introduced in the Ampico A grand, it carried over into the
Ampico B design and became an important factor there, too.  Duo-Art
collectors like to point out that those pianos always had loud pedal
compensation.  That compensation is achieved through the roll coding
scheme.

I had advised John Kiszla to seek these parts from this group.  Now you
know why.

As a small aside, a recent thread about tracker bar pumps and their use
leads me to explain that pumping the tracker bar _expression_ holes on
the Ampico A will never do anything.  The automatic cut-out acts as a
one-way check valve which prevents even the strongest of tracker pumps
from drawing anything through that device.  Not to worry, because the
lint traps can hold a lifetime of lint.  If the tracker tubing entering
the automatic cut-out is removed, a tracker pump can clear those lines
if that is a problem source.

Good luck to John,
Bob Taylor
Missouri