I have been working on a Welte (Licensee) for several months now.
The instrument had been restored not too long ago (10 years) but
the Welte had not used for years; everything was out of regulation. 

I have been playing the piano, adjusting it "just right" between
the player action and the piano action, fine tuning the expression
controls, and all-in-all getting it to play just as it should.

I have fairly extensive experience with the Ampico A and the Duo-Art
yet I have a few questions about the Welte which remain unanswered,
even after study of the Welte (Licensee) materials ("How To Regulate,
etc.") as well as the MMD Archive and Craig Brougher's insightful
treatise.

1. What is the proper adjustment for the "Selector Valve Chest Air
Governor?"  Clearly, the higher the tension is set on the spring, the
quicker the valves react and the quicker the hammer-rail lift moves.
The adjusting screw on the stem can travel more than an inch and a half,
which is a pretty large range of adjustment.  Is it best to measure this
adjustment with a gauge or ruler?  I found, in general, the less tension
on the spring, the better everything seems to work; however, how loose
is too loose?  No available literature seems to mention this adjustment.

2. The coil springs on my piano for the "Expression Governors" are
two different sizes and their fixed hooks (one on either side) are two
different distances from the moving hook affixed to the "Expression
Governor."  The current springs are Treble: 4-3/4" just the coil,
5-3/4" hook-to-hook; Bass: 5" just the coil, 6" hook-to-hook.  The
outside diameter of both springs is the same at 5/8".  Fully open,
the "Expression Governor" hook is 6" from the fixed hook on the Treble
side, 7" from the fixed hook on the Bass side.  Clearly, the Bass hook
could have been stretched out at some point; however, that wouldn't
explain why the fixed hooks are at different fixed distances.  This
piano does _not_ have movable/adjustable "fixed" hooks.

What should the correct size coil springs be? What distance should the
fixed hooks be from the "Expression Governor" when the "EG" is fully
open?  Is there a reason for the two sides (Bass/Treble) to be different
in spring length and distance?

This may or may not be related but thought I would add, just in case:
on 1 in 100 rolls, I was also experiencing some droop on one or two
chords.  Surprisingly, not during large, loud chords, but during
mezzo-forte playing with no more than 4 notes playing at one time.
I tried switching the two springs around, thinking that perhaps they
got mixed up at some point; that didn't help at all.  Then I moved the
fixed hook by temporarily holding it in place, slightly further away
from where it was originally installed.  This seemed to improve things
and also give a greater dynamic range and quicker dynamic response.
Would increasing the hook distance or spring tension reduce the droop
in medium/soft passages or is this my imagination?

(I also went through the note repetition test with a gauge making sure
there was even vacuum being used by each of the note pneumatics and to
make sure none of the valves or note pneumatics were leaking.  The
gauge showed every note was uniform.)

3. Many sources have said "the literature is a starting place; always
test by ear" which is true of all reproducers I suppose.  It seems,
however, that many of the early Welte rolls, especially popular tune
rolls, are not coded very well (between 6000-6500 roll numbers) and
have a fairly bland dynamic palate.  Is this just my instrument or are
these rolls badly coded?  What are the best rolls to use when testing
expression regulation?  Clearly not all rolls are equal and it has been
frustrating tweaking the piano to play one roll well, only to have it
play less well on the next roll.

Thanks to anyone who can offer some advice.  I always enjoy reading
the forum and hearing from fellow enthusiasts.

Regards from Burbank, California,

Adam Aceto