I have recently had a run-in with a '60's-'70's Kimball player with the
roll in the bass end top lid loader type.  Some of them have the volume
and tempo knobs in the bass key cheek.  They usually have motor gear
problems but I will not address that as this one does not have that
problem.

I did, however, have problems with not enough suction from the pump,
or so it seemed.  I found that the clear plastic duplex valves were
glued to the maple deck board with airplane glue and it, of course,
had come loose.  I found most of them were loose.

To remedy the situation, I cut a cork/neoprene gasket for each one with
three holes in it for wind.  I sanded each of them to get them flat
once again.   I then drilled two screw holes into opposite corners of
each valve unit.  I installed that and then found to my horror that the
stack still leaked.  I had checked the valves, they were made of gum
rubber and were fine with only blowing out the dust.

I looked harder and found that most of the valve blocks leaked at the
seams, at the seams that had been sealed with industrial airplane
cement.  I could suck air right through the sides of the units.

I have now sealed all of them with shellac, just like Ampico Valve
blocks, and am in the process of re-installing them.  I have checked
each of them and they are definitely totally air tight.  The only thing
I now fear is that the electric vacuum motor is now running slower, as
I have found to be the case in many other 30 year old suction boxes.

These little valve blocks are a very good design.  If they were only
brass ... The mind wanders....

If anyone e-mails me, I will be traveling to Denver to install a
theater organ, so answers will be late.

D. L. Bullock    Piano World   St. Louis