Bernt Damm from Cape Town is having problems with his sustain.  The
speed of the sustain pneumatic can be tricky on some players.  It can
be any one of a few things.

Valve travel can affect how fast the sustain pneumatic works.  If the
gap is too small, it can not move the air as quickly.  Your gap size
seem reasonable but increasing it could help.

Another problem may be that the valve seat leather is not glued down or
has separated and pulled apart around the edges.  This causes the value
to not completely open up when the value is turned on under vacuum.
The value travel reads okay but the value is starved for air movement
because the leather is pulled back to the value seat because of the
vacuum.

The sustain not turning off as quickly could be because of the above
mentioned problem, but not usually.  All of your problems may be
because the sustain pneumatic operating distance is set too large.  If
the dampers on the piano are not regulated very well and don't lift off
of the strings at the same time, then you have a tendency to adjust the
sustain linkage to compensate for the poorly adjusted dampers.

The shorter the distance that the sustain pneumatic has to move, the
less distance the dampers have to be pulled away from the strings.
This effectively speeds up the activation and deactivation of the
sustain function.

Press the sustain pedal down with your foot and look at the dampers.
Do they all come off of the strings at the same time and the same
distance? If they don't, try regulating them and readjust the sustain
pneumatic so it doesn't have to open and close so far.

Friction and even extra thick felt between the sustain linkages can
contribute to a lost motion problem.  Replace with wood shims and thin
action felt between the pneumatic arm and the stick which pushes up on
the steal rod behind the action.

Damper springs in the old players loose their spring over time.  The
damper springs press the dampers onto the strings.  If they are weak,
then the sustain won't turn off as fast.  The sustain turn off time is
contributed by all of these springs pressing against the sustain
linkage and the pneumatic.  Note: changing the damper springs changes
the touch of the piano.  It can also contribute to missing key problems
at lower stack vacuum levels if the springs are too heavy.

Pete Knobloch (Tempe AZ).