I have just stripped a Kastner lower action for re-covering.  It
comprises the usual pair of pedal bellows, each with a front mounted
reservoir.  The left bellows supplies suction to the stack via a
governor.  The right bellows supplements the suction to the left
bellows and also supplies suction to the air motor.

However, upon inspection, I find that the right hand reservoir has
two internal springs but the left hand one only has one.  The two in
the right hand reservoir are 6" and 8".  The single one in the left
hand reservoir is 6".

Am I missing one or was it built that way?  The cloth support strips
are there, which suggests that the spring has been removed, but there
is no obvious other sign of previous restoration work.

Any help appreciated

Roger Waring - The Pianola Workshop
Solihull, United Kingdom
http://www.pianola.co.uk/