John Grant's well-written article on this subject brings forth a
question that was addressed thoroughly in the DVD that I released
titled, "The Ampico Code Part Two".  The DVD was first available
in 2012.  Information about the DVD can be found at
http://aeolianorgan.com/Ampico/Technical_DVDs.html 

At about the 18-minute point in the DVD, the "Missing Ampico Intensity"
is fully explained with regard to the Ampico A system.  Later in the
DVD, that "Intensity" is also explained in the Ampico B discussion.

The 1919 Service manual gives that intensity the title of "alternate
setting."  As a student of coding, I can state that the 2&4 setting is
used frequently and that it renders an intensity slightly less than if
hole 6 were used alone.

In support of the assertion that the Ampico indeed does possess an
initial set point called the "First Intensity", I submit this image of
an original placard attached to a beam of a Mason & Hamlin RCC concert
grand Ampico piano.   The factory referred to this piano as "RCC Ebony"
as the only other Ampico A in a concert grand Mason & Hamlin was in
a wood finish.

Bob Taylor
Missouri

 [ Original pressure placard on Mason & Hamlin concert grand, demo piano
 [ http://www.mmdigest.com/Attachments/15/09/24/150924_191305_J1751x1468-00136.jpg