[ Ref. Robert Nicol in 181112 MMDigest ]

Hello, Robert, from the other side of the pond!  I have been working on
Ampico mechanisms for over 40 years.  Yours is a very common problem.
The first question would be, "When were the secondary unit block valves
rebuilt?"  The next question would be, "What material was used?"

The players of that vintage have upside down valve blocks.  When you
first turn on the player the valve cores need to be "sucked up" in
order to seat.  So what is occurring is 83 small leaks.

When you put the Tempo control on zero it allows the suction to be
directed only to the stack hence allowing the valves to be "sucked up"
and seated.  With time, the valve travel increases, mainly because of
the gasket material used under the top seat -- it swells with age,
increasing the valve travel and so it is harder to suck the valve into
place.

When rebuilt you can only use leather, not neoprene.  I have seen
some rebuilders use this and it does the same thing because the valve
clearance cannot be set properly.  The Ampico grand at the NAMM Museum
is experiencing the same problem.  It is a big job to rebuild all of
the valves but that is the solution to the problem.

Another trick that you can try is to put the Tempo at zero and push
the two expression buttons on the bass side to increase the amount of
suction to the stack.  But the first thing I would do is to test a few
valves.  What is the valve travel?  It should be set to around .031"
to .033".

Take a few valves apart and check the condition of the valve leather.
If it flakes off, or if it turns out to be neoprene, you need to
replace it.

Good luck!

Diane DeTar
La Mesa, California
ddetar49@gmail.com.geentroep [delete ".geentroep" to reply]