Paul,
I would think that area of the plate should be under compression. Thus, to me, the tension up there shouldn't be of great concern. I mean, a couple hundred pounds (the potential difference between 13 and 13.5 wire for 6 unisons, for instance) either way didn't cause that failure. That's my thinking. Thus, to me it looks like some kind of defect in the plate casting (bending over the pinblock, maybe?), not prolonged string tension stress. The compression provided by string tension should only help hold the thing together. Thus I'd just buckle that puppy down to the pinblock and hope for (assume??) the best! Heck, it's probably been in that condition for decades, and the local plate screws seem to be managing it. If I remember correctly, the person who wrote the original message and provided the photos said the piano was up to pitch up there. Therefore in my admittedly brief study of the thing I said the situation looked safe.
Geez... I have to watch what I say out there! :-) And seriously, this is exactly why I don't work on old uprights. I concede there's tons of money in it, though. Anyway, there is enough mind trauma in restoring in quality grands with structurally sound plates.
David G. Hughes, RPT
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