From time to time I hear discussion of the adjustment feature of
Wurlitzer unit block valves as they were originally made.  I am curious
about this.  I understand the importance and significance of proper
clearances so the valve responds quickly, opens far enough to pass
enough suction to its device, and allows only a minimum of suction to
escape while it moves.

How are these valves adjusted?  If it is necessary to dismantle the
valve, then the effort is more than the value of the adjusting feature.

How would a properly adjusted valve get out of adjustment?  If the
leather gets so beaten down from long use that the clearance changes, I
am suspicious about that matted leather's ability to seal properly.
Wouldn't it be time for a new valve?

Are there any old-time carny servicemen reading this forum that can say
for sure whether adjustments were commonly made in the field 60 to 90
years ago when the performance of these machines mattered?

The few replacement valves I bought in the 1960s or 70s had a neoprene
button which was not adjustable.  They seemed to perform just fine and
they may still be playing on my Wurlitzer 153 band organ.  I had a
well-respected local restorer rebuild a few of my old unit blocks.  He
covered the pouches (bottom of the blocks) with pneumatic cloth.  I
questioned this.  He said they'd be fine; he was right.  I've had that
organ for forty years and it has played reasonably well for most of
that time.  But what do I know?  I can only judge from the compliments
I got when it was out in the field for many of those years.

Doug Hershberger
Martinsville, New York