On the subject of historic restorations, recently I restored an
Ampico Fischer upright with a nameboard that folds double and pushes
back, exposing the hinge just over the keys.  This kind of a case
requires an extra half-inch that was subsequently taken out of the
piano action, leaving very little adjustment for the piano action,
itself.

   They used half-thick damper felts, for example-- unobtainable today,
unless you decide to just make them yourself, but the bass dampers were
also shallow to match and those you cannot make yourself.  Better just
to use a matched set.  Replacing the dampers sets the damper wires very
close to the spring rail, too.  The damper spoons then have to be bend
far forward to lift the dampers.

   The biggest problem was the modification (thinning) of the main
piano action rail molding which sets all the parameters for adjustment,
anyway.  It places the jacks too far forward under the butts, and the
let off screws barely touch the jack toe before the backchecks begin to
touch the catcher buckskin.  In other words, this is a trapeze act whose
swings are too short.

   What to do? The best you can hope for is to get the piano initially
set so that the hammers will check short of the strings and will not
bobble, but without any latitude of adjustment, how long should one
expect this idealistic regulation to last? There is a fix, but it
requires an action modification, so I would have to say that a history
buff would not appreciate it, but a music lover would.

   I think that on this subject, we should value good tradeoff sense
and balanced judgment.  Factories made mistakes, and changes, even
within a model year.  In all, I have never run into two pianos exactly
the same in my life.  Who's to say that some modification wasn't
experimental, was taken home by some employee, sold after awhile,
re-purchased and restored? I personally know of two instances of this
happening.

   As in automobiles, the most important "historical" features, and the
features graded at auto shows seem to be those which are of an outward
appearance.  There is no way to tell what valves, cam, and rings the
guy used.  Are his bearings babbit? "Forget bearings.  We'll look at the
spark plugs and judge them." Whatever the eye can see is what the
authenticity advocate is most interested in.  When they start
complaining that something has changed from original because the
hammers aren't bobbling or blocking the strings anymore (like that
particular piano was supposed to do), then they've got the problem--
not you.

Craig B.