Need help. (was Sanding Bridge Tops)

[tom driscoll]

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To: "Pianotech"

> List, I need your help.
> Today I tuned a Young Chang U-121 upright piano, purchased 20-25 years
ago.
> I found the bass very out of tune, uneven.
> Customer tells me her previous tuner had problem with bass, but couldn't
> explain why.<SNIP>
>
    > My thought: Loosen bass strings off bridge (do  need to loosen all
strings to
> prevent plate cracking), <SNIP> Bruce Browning - The Piano Tuner.
>
>Bruce,
    I'm not sure about the cause of this bass tuning problem but the plate
will not crack if you remove the bass strings.
    Others have expressed this concern , including myself  (30 years ago) .
    The plates integrity would never be dependent on the tension of the bass
strings .

    Back  to the tuning instability ,
    Did you have to pitch raise the bass more than the rest of the piano?
    How long ago did you tune this thing?
    What was the R.H. @ the piano and has it changed dramatically ?
    Did you tighten plate screws around the block area?

    A shifting pinblock comes to mind ,but you're the one with the eyes at
the piano.
    Best wishes,
    Tom Driscoll RPT