Well, I have been dreading this for at least twenty years.  I refer
to rebuilding a more recent Aeolian Pianola which uses those blasted
plastic Amphion-style right-side-up valve blocks.  I cringed when I
thought about having to ever rebuild one of those beasts.  But I have
now gotten into it and it is not so bad.

Do you know why these plastic valves are clear, orange and red?  They
were made from car tail light lenses that did not pass quality control!

The pianos are now twenty to thirty years old and they never played all
that well.  The main problem is that the valve travel is usually around
80 thousandths inch.  The valve itself is made out of sponge neoprene,
and you know how that stuff fails.  For those who don't know, it seals
completely for a few months after installation, but then the face seems
to wear off and it begins to seep.

Durrell Armstrong, of course, back in the early 1970's, advocated using
it for valves and I experimented with it on my own Duo-Art, but it was
a complete disaster.  It played very well for a few months, but then
I found I had to stop the roll before I played it and crank the stack
pressure way up and listen for all the valves to suck down and seal.
Then I could play the roll but would have to do it all again on the
beginning of the next roll.  Watching the gauge, I could see pressure
in the stack go from 3" to off the end of the dial as the valves sucked
down.

I am presently rebuilding a 64-note Aeolian Pianola from 1975.  These
and the 88-note units have several common problems.  Among them, they
are usually quite breathless and the electric motors usually need
replacing.  Because of the wide valve travel you can forget good
repetition or playing softly.

This one would play very weakly when I got it.  Since I had to go
through the piano action, I pulled out the spool box and tracker tubing
which was all very hard by now.  You can't get to the piano action and
keys until you pull out the spool box (a royal pain in the patootie).

I checked out the stack and found it quite leaky when sucking on the
supply by mouth.  I also checked the striker pneumatics and found them
also beginning to develop holes along the creases.  I decided I could
not put it off any more and pulled the stack for a complete rebuild.

The valve blocks must be chiseled off, but I only had 3 or 4 break
enough to need to glue them back together.  One broke badly enough to
need to replace it.  Once they were all off, I sanded the wood shards
off and popped them open with a twist of the chisel tip placed in the
supply holes.  The sponge neoprene valves were very ready to fall
apart.

Because of my experience with natural gum rubber in 30- to 40-year-old
players and 1920's pipe organs, I replaced the valves with a biscuit of
thick gum rubber.  I found I can stretch the center hole with needle
nose pliers and pop the old valve stem wires into the new valves.  The
stretched hole snaps back into place like it was made for the original
valve stem.  Then I can measure valve travel and sand off the plastic
tops until I have a reasonable valve travel when I glue them back down.
I am setting them to 28 to 30 thousandths which should allow for soft
playing.  You can test any valve block by mouth and you cannot get any
seepage to come through the gum rubber.  We know it will last 50 years
or more, too.

I also replaced pouches, sealed them and added a cardboard disk.
I also am adding a felt disk to take up the huge amount of lost motion
between pouch and valve stem.  Most of these valves had a disk of
sponge neoprene which had come loose from the pouch and just rattled
around in there when it played.

The pneumatics came off slowly and with difficulty using a hot iron,
but I only had to make a couple of new boards from the whole set.
I had to sand down the decks so I can glue back the valve blocks.

This is a stack I can rebuild in a week and have playing far better
than it ever sounded new.  Now if only the piano itself sounded any
good.  I haven't even tested the lower bellows yet.  Those will
probably need everything as well.

When finished I will put this piano in the museum and let thousands
of people play (shred?) a large cabinet full of rolls.  It should get
a good workout and we will see just how much abuse the little piano can
take -- perfect for testing the new rebuild technique.

D. L. Bullock    Piano World    St. Louis