What about rusting the pins? The plate? I believe that while some pinblocks may fail from drying out, most of the ones I have come across were just not very good to begin with (poor quality wood, not seasoned, etc.) or simply worn-out (I have come across old pianos that were tuned frequently throughout their life and just as a screw in a piece of wood that has been retightened often will eventually strip the fibres of the wood, a tuning pin does the same thing on a much smaller scale of course
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