If the backcheck does not touch the hammer on the way up to the string, it can have absolutely no effect on the tone of the piano. The hammer would have no way of knowing if the bachcheck is close or far away, so it can make no decisions as to good tone or dead tone. The foolproof (read bullet proof) method to insure that the backcheck does not lightly graze the hammer tail, is to place resistance pressure on the hammer while pressing the key down. This test can be done in the piano or outside the piano. do not press key down to let-off point, but just short of it. You can rock back and forth to sense the slightest touching. For those of you who have seen the slow motion movies of a hammer striking the string, you know that the hammer wobbles every-which-way on the way up to the string. When you do this test, make sure that you are pressing the hammer forward to simulate the worst-worst condition. If the backcheck passes this test, there is no way that the tone can be affected by the backcheck. Jim Coleman, Sr.
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