Patrick, First I would check to make sure the dampers are seated properly. Partials can ring if the front or rear portion of the damper seats unevenly. I have solved many such problems with new (Yamaha) dampers. I use Yamaha damper felt because it seems to dampen more efficiently. If you want it to look like Steinway felt just don't use the red under felt. Although the red under felt does help the damper work more effectively. If they are a serious player, as you stated, then 20 years is a good time for felt replacement. Sometimes just readjusting the damper felt or voicing the dampers can help. I have even trimmed dampers for better contact to the strings with great success. Ed Tomlinson
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