These lost motion pneumatics are not always on an Ampico stack.
Several variations of stack were used.  If present, at least two of
them and often three of them are found in many stacks.

First check to see that the aluminum rail covered with felt is under
the flanged fingers that push the keys.  This should be moveable and
is hinged by additional wooden fingers, but without the capstan, and
they will attach to the lost motion pneumatics

The positions of the lost motion pneumatics do not have valve blocks.
They are positioned where the nipples out of the treble and bass sides
of the stack come out to go to the amplifier box (with the pouch/valve
and the two little flap valves inside).

Each pneumatic has an elbow or tee connector coming out of the top
and they all connect together with tubing, 3/16" I believe.  They are
activated from the smaller nipple that comes out of the soft pedal
pneumatic valve block.

There should be a block with two Ampico valve blocks on it.  These have
bleeds and one goes to the sustain pedal pneumatic and the other goes
to the soft pneumatic and the lost motion pneumatics as well.  In the
1927 units this will also feed a tiny 1" x 1" compensator pneumatic
mounted to the back side of the spring pneumatics on the expression
units.  That is not found on other year models.

Replacements are easy to make.  I have made many of them.  They screw
to the decks and the holes to those screws in the moveable board are
covered with disks of bellow cloth for access to the screws.  The metal
push rods for these are seldom straight up but may have a couple of
dogleg bends in them.

The moveable board will have what looks like a long key capstan with
holes in it like in a grand key.  This goes up into the pneumatic and
hits a felt pad inside and it will enable you to adjust how far the
wood fingers lift.  They should only lift enough to stay in contact
with the backs of the keys when the soft rail is activated and no
farther.

Doug L. Bullock