CP contamination on Yamaha S 400-B

[jolly roger]

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Hi Mark,
              Some older Yamaha's had a centre pin plating problem, if you
look
at the pins under a magnifying glass you will see score lines on them and some
flaking. The only solution is to ream all bushings and re centre pin 2 sizes
over. 
This will get the crud out of the cloth, I also blow them out with compressed
air.  About 25yr old vintage.
Roger




At 08:06 AM 5/4/01 -0400, you wrote: 
>
>   I had a customer complain about the touch on their Yamaha grand and
> discovered that it weighted off at 66 grams at middle C. When I checked the
> hammer flange I found that I could only get one swing, and that the bushings
> had a black residue on them. Closer inspection showed that this residue was
> also on the center pins as well as slightly in the wood surrounding the
> bushings. The residue on the pins themselves rubbed right off, and the pins
> looked shiny and new without any signs of buildup or corrosion. I repinned
> one to normal tolerances and the cloth felt as if it had normal resiliency,
> and the downweight dropped by 11 grams. I also found that the wippen flanges
> had the same residue, but hadn't seized up the way the the hammer flanges
> had. They seemed to be *slightly* on the tight side but still within normal
> tolerances (I didn't have my little spring gage with me). The jack & rep
> lever bushings were normal bright red cloth, and perfectly free.
>   I have an appointment to return and repin this action, but before I do I
> wondered if anyone else has run across this before. Could this be something
> that Yamaha did at the factory? although I've certainly never seen it in
> their other grands, this is the first S series grand that I've serviced. The
> customer bought it used last year and so doesn't know it's history. Does
> anyone know of any center pin lubricants that react in this way? Is the
> problem likely to return after repinning? The serial # is: U3894763
>  
> Thanks, 
> Mark Dierauf




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