Mystery Noise

[Vanderhoofven]

Dear Friends,

I have a mystery noise that is baffling me and irritating my customer.

The piano in question is a small, older Osborne grand.  The hammer shanks
have no knuckles, instead they have leather covered "bumps" on the hammer
shank.  Also, the wippens have brass billings flanges instead of wooden
flanges.  This piano also does not have a una corda pedal or sostenuto
pedal. Instead, the keyframe is screwed down to the keybed and the left
pedal lifts a rail that raises all of the hammers closer to the strings
(similar to the way an upright piano soft pedal functions).

The mystery noise is like a rattle, and is located in the first note past
the bass/treble break - note A#2.  Although the overall "noise" level of
this action is rather high, this particular noise ("rattle") is not in the
key, wippen, hammer, shank or flange.  The noise is not from the soundboard
or ribs or any loose case parts.  After inspection with a small mirror and
light, there does not appear to be anything laying on the soundboard that
would make a rattle like this.  The noise is isolated to the damper
underlever, wire and damper head.  The damper underlever flange screw is
tight, the screw that secures the damper wire into the underlever is tight,
and the damper wire is tight in the damper head.

Possibilities...  The two small leads in the underlever were slightly
loose.  Whereupon I promptly swedged them, splitting the wood of the
underlever.  (Oops!  My mistake.  I know, I know, I can't afford to
purchase a pair of the Renner DeadLeader pliers yet.)  Once the underlever
was reglued with Titebond II and the leads were secured, that did not seem
like the cause of the noise because the noise is still there. 

One other possibility:  This note right past the bass/treble break has the
damper head offset quite a bit because of the plate strut. The damper guide
rail bushing is worn out and the wire has a lot of loose play.  The damper
head and wire do vibrate quite a bit when the key is played, but the rattle
is not caused by the wire or damper head touching the plate, the adjacent
damper head and wire, or any of the strings.  I do believe that the noise
is coming directly from the contact of the damper wire with the worn out
guide rail bushing.  Lubricating the damper wire has little to no effect on
the noise.

Question:  Is it possible to rebush an individual damper guide rail bushing
with the rail still in the piano?  Removing the guide rail and rebushing
the entire rail is out of the question because of the quality of the
instrument.

Suggestions are welcome, and will be forwarded to my customer who is also
on the Internet.  If you don't want your answer forwarded to my client,
please let me know and I will respect your privacy.

Thanks for your help!

David


David A. Vanderhoofven, RPT
Joplin, Missouri, USA        
e-mail:  dkvander@clandjop.com

web page:  http://www.clandjop.com/~dkvander/
#pianotech page:  http://www.clandjop.com/~dkvander/ircpiano.html