Greetings,  At the risk of nasty backlash I have to make a comment
about Duo-Art regulation.  I don't care about the "Go/No-go" go test.
I just adjust the piano to sound good and have a nice straight vacuum
plot.

Every piano is different and it is just not possible to pass the
tests sometimes.  Consider a few of the variables and then decide if
all pianos should pass the test.  The manufacturers provided the test
as a quick way to crosscheck a few things.  It was never intended as
a strict rule.  I can make a Duo-Art pass the test and sound awful.
Mine sounds great.

Different pianos had different size pneumatics which would use
different amounts of vacuum and therefore bias the test.  Mine has huge
graduated pneumatics.

Piano actions are different.  Overcoming the base friction may be
a smaller or larger part of the total power required for a strike.

The test rolls are different.  I scanned several over time and found
that the number of notes in the "Play/No-play" test varied over time.
I even found a roll which was completely different in its ratios, and
it was an original Aeolian issue.  Maybe it was for a special purpose
but this was the first one I had and it drove me nuts.  It just plain
would not work.  As the design changed, the number of notes probably
did and it really would be necessary to have the roll to match your
piano and still it is just a check, not a test.

I would never put in flimsy springs to make the test work and have a
dead piano.

The only way to perfect a Duo-Art is to set it to produce a graduation
of levels (either conventionally or with accordion settings chosen to
produce the required binary scaling) and then play many many rolls and
fiddle.  Of course, everything has to be in good condition to not have
interactions that can not be compensated for.

Radical changes to one aspect of this complex system will never work
to compensate for problems elsewhere, and there may not really be any
problems except a test that is wrong for the piano.

Best regards,
Spencer Chase
Laytonville, Calif.
http://www.spencerserolls.com/