I have a couple of Steinway upright pianos and, although they never
seemed to get severely sticking center pins, there was a little
unevenness in the amount of vacuum needed to play various notes.
When my piano was rehammered, the piano technician applied a magic
solution to all the center pins.

The result is that the piano plays perfectly with a 'zero' setting of
3.5 inches of vacuum on the Accomp. and 4 inches on the Theme.  It plays
whisper quiet (rare for a Duo-Art) and does not miss a note.  You can
hear the softest notes just kiss the strings.  I imagine the piano
could do that when it was new or after a very careful repinning job,
but this is a 75-year-old piano.

Oh yes, the magic solution is called "ProTech" and it does not smell
like "Goof Off".  In fact, it does not seem to smell much at all.  It
must be some kind of micro-encapsulated stuff.  It leaves no noticeable
residue on the nearby wood either.  It is quite expensive but cheaper
than a repinning.

Spencer Chase
http://www.SpencersErolls.com/