Hi, Jerry, Check that the dampers are not resting on the backs of the keys. Place your fingers very lightly on a key and lift and drop the damper. If you can feel a bump at the end of the key there is not enough clearance. The key should go down 1/8" or the hammer half way to the string when the key and damper lever come togather. You can get some ringers from the entire duplex, from the middle section to the high treble. All the duplex needs to be muted to test if they are the source. I have used fresh black electrical tape because it does not leave adheasive behind when removed. I carry silly putty to use for this purpose while tuning. IF the sounds continue then mute the open treble strings. This is not much you can do about them if they sing so work with the customer during the entire process of elemation. If it is one or two duplex singing you can use some thin felt to mute the offenders or you can smear some vasaline on the offenders. It is invisable and can be easily removed. Let me know how this works out. Newton
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