In 011207 MMDigest Nathan Bello tells us his Ampico only plays at about
half the intensity or force that it should.  This could be a number of
things.  You mention it also looses quite a bit of suction whenever the
sustain pneumatic is turned on.

Remove the sustaining pedal mechanism and test it for leaks in the
pneumatic, especially in the hinge area.  Test the valves for leakage
too.

Be sure that everything is correctly tubed.  Test by blowing air from
the source to see that it comes out at the correct switch or tracker
bar hole.

Check the subdued switch to see that it is connected correctly and that
both subdued unit valves are not leaking and the valves are seating
properly.  There are no allowance for leaks of any kind in a properly
rebuilt Ampico.

One problem could be the cancel pneumatic arm on the expression cutout
block.  It is a fussy thing and has to be perfectly air tight and in
perfect alignment to seat correctly over the two nipples for 7B and 7T.
(Perhaps that is the reason it was eliminated in later mechanisms.)
To test this theory, remove both 7 intensity tubes from the Automatic
expression cut out block and connect the tubes directly using two
elbows.

Another problem that is overlooked is the amplifier control box
(Illustration No. 10 in original manual).  The valve must seat
correctly every time when the switch is set at brilliant.  The valve
stem (11) should allow the valve button to flex.  If the valve stem is
glued directly to the valve button, break it off, and glue a small dot
of felt between the valve button and the valve stem.  You may need to
shorten the valve stem to compensate for the felt dot.  By doing this,
the valve will seat correctly each time it is needed.

Check the automatic expression cut-out block.  Is it tubed backward, or
is it leaking?  Tubes from the tracker bar must be attached at the side
farthest from the removable gasketed top.  Sometimes in rebuilding
these get reversed.  To test for leakage, temporarily by-pass this
block, using 14 elbows to connect the tubes directly.

Test your pump and stack vacuum:

1. Cover the tracker bar with masking tape, set the repeat lever to "on"

2. Set the tempo at 75

3. Remove tube 1B from the bass crescendo, and remove tube 1T from the
treble crescendo.

4. Set the modify switch at Medium

5. Take a reading with an accurate vacuum gauge.  The reading should
be 20" water gauge.

6. Set the modify switch at Brilliant.  The reading should raise to
between 27" to 30", but not more than 30".

If you are not getting these readings you will need to make adjustments
by rotating the medium adjustment spring on the top of the pump (the
longer one).  The Brilliant adjustment is the screw on top of the
amplifier pneumatic.

The very soft settings are set with the screws attached to the springs
of the crescendo pneumatics.  They should be set as low as possible,
but high enough that notes are just audible, with soft pedal on.

Bruce Clark