In response to questions by Pat Dewitt:  According to Yamaha there are
37 steps to grand regulation and most of these steps are done 88 times.
If one of these (x88) steps are done incorrectly or in the wrong order,
it will mean that most if not all steps which follow will be incorrect
because an adjustment in one place affects things in other places
errors can magnify as you progress.

Knowledge and the right kind of experience are needed. Consistency
and accuracy improve with experience.  In the first several actions
I regulated, my work was not of the quality worthy of your Mason and
Hamlin.

From my experience Steinway and Renner Blue hammers are mellow, often
extremely mellow.  You mentioned you want a bright sound, so hardeners
may need to be added to these hammers.  The tone usually has to be
built up on these.  Renner hammers for the European market and Abel
hammers are more bright, often too bright for the taste of most
Americans.  These are usually not the hammers for someone who likes
a real quiet pianissimo without voicing.

If you replace the hammers also replace the shanks so you don't have to
go in later and redo the hammer and regulation work after replacing
shanks.  Renner, Brooks Ltd., and others sell hammers and shanks
pre-hung (on the shanks), costing a little extra but saving some labor.
I am skeptical about whether pre-hung hammers are the way to go.

Whippens can be reconditioned but, if the repetition springs are too
weak or metal fatigued, I would also order a new set of whippens.  For
your Mason and Hamlin you should be able to find the correct parts new.
I would go to the web site of Piano Technicians Guild to find an expert
and talk with that person.

Bill Maguire