While I've never heard of a Kastner player action, it certainly is
possible that the valves are being slightly activated because the
pouches have shrunk do to dryness.  However, when that is the case,
pumping the unit very hard (quick) will usually allow the valves to
seal.

A fairly quick way to remedy the problem of shrunken pouches is to
remove the pouch board and "stretch" the pouches with your finger.
Just place your finger near the edge of the pouch and move your finger
in a circular motion around the edge.  This will increase the dish
(even if only temporarily) of the pouch and that will allow the valves
to seat properly.

If the problem still persists, it might be that the valve buttons are
set a bit too high.  So the next step would be to lower the height of
the buttons by 0.010"-0.020" [.25-.50 mm].

If that doesn't solve the problem, you most likely need new valve
facings!  Depending on how the valves are designed, it's quite possible
that the leakage is occurring at the point where the intake face is
mounted to the shaft.  This is not uncommon.

Although some rebuilders/technicians might raise their eyebrows at this
suggestion, I've found that an effective temporary repair is to apply a
tiny bead of Phenoseal around the shaft where it meets the valve facing
(on the intake side).  Having performed this procedure more than a few
times for customers who simply couldn't afford a complete valve job,
I can testify to the fact that performance increased over 50% simply by
sealing the intake valve facing to the valve shaft with a flexible
sealant.  Usually, this procedure can be accomplished without removing
the valve if you use a hypodermic-type applicator.  And the whole
process takes less than an hour.

(I can sense that I might take some heat for this suggestion.)

Musically,

John A. Tuttle