[ Ref. Rob Buskop in 150324 MMDigest ]

Replacing grand piano hammers is an involved task, especially when,
as in this case, they have been previously replaced and there is no
guidance in the installed parts.

Hammers are directly linked to touchweight and inertia issues in
grand pianos, not to mention tone.  You cannot simply replace old
hammers with "similar looking" ones and expect a good outcome in the
playability and tone department.  Proper hammer replacement requires
a deep understanding of action geometry, touchweight analysis, and
the steps and techniques (not to mention the specialized tools and
jigs) for hammer preparation and boring, hanging and regulation.
This goes far beyond what the average hobbyist has at his disposal.

There are essentially two choices: either buy some off-the-shelf
parts and install them, and live with the resulting poor performance,
or else hire a professional for that part of the job -- everything
from action analysis, parts selection, installation, set-up, regulation
and voicing.

Or, of course, spend a few years studying this in-depth aspect of
piano technology.

Jurgen Goering
Nanaimo, British Columbia, Canada
http://www.pianoforteservice.com/