[CAUT] buzzing truck

[johnsond]

Hi all-

The truck on our #2 performance piano has a problem buzz.  It has been 
elusive for some time mostly because it's been difficult coordinating 
the occurrence of the buzz with someone else available to play the note 
while I check things out.  This finally happened yesterday.  All bolts 
are tight.  When we play a Bb there is a buzz coming from somewhere 
between the top and bottom center plates.  Laying only the weight of my 
hand on the top plate makes it stop, remove my hand and it comes back.  
It does not sound like any stray material is inside but it will not be 
possible for me to remove the truck until summer sometime. What I did 
was loosen the suspicious bolt about half way which allowed the plates 
and arm to reposition slightly, then re tighten.  I have not been able 
to make it recur since then.  It is a standard Colson truck from 
Jensen's that I guess is about 15 years old.  I am inclined to recommend 
just replacing the whole truck as I was expecting to replace the wheels 
anyway this summer.  As anyone else experienced a similar problem with a 
truck?  How long do you typically keep them on performance pianos?  Any 
other suggestions.....?    It needs to be resolved with confidence. 

thanks,

Dennis Johnson
St. Olaf College