Hi all,  Just a quick addition to this thread.  Personally speaking,
I've never been able to strike a key with enough force to set the
pin using only one finger.  I've tried it many times, and my finger
gets really sore in a hurry.

So, I use a 'three-finger' technique that I read about in E. J.
McMorrow's book "The Educated Piano".  He uses his thumb, index
finger, and middle finger to, as he puts it, "sock" the string "to
set it into tune at the optimum point".  He goes on to say, "If you
use just one finger for your test blow, it can be hard on your joints."

Also, earlier in the chapter on Unisons and Tuning Stability (pages
54-58), he makes a statement the I often paraphrase: "If the pianist
can change the string's pitch, the piano was not tuned!"

Musically,
John A Tuttle
Player-Care.com
Brick, New Jersey, USA