Upper Notes with Low Sustain
by Steve Woodyard

There are occasions when the upper notes of the piano do not sustain or loose their sustain over a period of years. This can be traced to a change in the apparent mass or loss of "freedom of vibration," of the tone bar/tine assembly.
The tine/tone bar assembly is a tuning fork with un-equal legs. One leg, the tine, vibrates more, but at the same frequency, then the other leg, the tone bar. Both parts are tuned for that specific frequency. The bar is gross tuned by its length. The tine is gross-tuned by its length and fine-tuned by the spring that acts like an adjustable weight. Similarities exist with a pendulum of the Grandfather clock and the mechanical metronome. Any change in the apparent mass of the tine/tone bar assembly causes a shift in the frequency it was tuned for and hinders its sustaining properties. This is more important to the upper notes then it is to the lower notes.
The tine/tone bar assembly is intended to "float" on its adjusting tone bar springs and is intended to be isolated from the mass of the adjusting tone bar screws by the rubber grommets that mount into the tone bars. Sometimes the tone bar springs crimp the inside of the grommet and allow the tone bar screw to come in contact with the tone bar. A loss of sustain results. After a number of years with the grommet being crimped, results in the grommet being permanently deformed. At this point you can do two things to improve or restore the sustain.
1. Replace the grommet;
2. Force the grommet to re-set.
You can attempt to get the existing grommet to reset by removing it and loosening it up by rolling it vigorously between your fingers. By doing this you are trying to get it to re-form to its original shape. This can be helped by soaking it in "Armour All," which is a protectant sprayed on car tires, before you roll it between your fingers.
Another thing that has caused the grommet to fail as an insulator is one of the types of tone bar screws that were used for a period of time. Originally the tone bar screw, which is a #8x 11/2, was not threaded all the way up its shank. The portion under the head, 5/8 inch, was smooth. Then, for a while, a fully threaded screw was used. Initially there was no difference but, after years, the grommet oxidizes and the threads digging into the grommet, help harden it. Insulation is lowered and sustain is affected. Massaging the grommet as previously mentioned plus filing down the threads of the tone bar screw should cause an improvement. Only file the threads down (not off), for about a 1/2 inch of length, that are under the screw head and that go through the grommet.