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OK Kiddos, it's Piano Technician Quiz Time!
This might new for some folk but may be interesting for everyone...

Customer Complaint: "It went way out of tune recently and was just tuned in March".

Technician observation: Mid-range on pitch and playable but tuning uneven. Tuning uneven in bass and off with mid-range. From C-52 the upper note each ascending octave is progressively 50 cents flatter than the previous one.

Here are photos:
[img]https://drive.google.com/file/d/173Ecl7PRX5Wvp-cCo6JyKFSrtLxJA2D7/view?usp=sharing[/img]

[img]https://drive.google.com/file/d/1nKBEv1JYBgZxmuNxvRcN24HmjoKhp7jL/view?usp=sharing[/img]

And your diagnosis is??

Pin block separation from the back frame.

Say Hi to a really old piano (85 keys) and the final result of having it in a really dry place.

Climate Change.

No, the problem is L.B.M. (Lateral Bridge Migration). Notice how all the strings are straight up and down? The bridges have moved sideways!!!

My money is on Toon.

Off topic, but that piano reminded me of a wine bar I saw on OfferUp today. https://offerup.com/item/detail/826463292/

How would the bridge move sideways?

The plate is twisted forward in the high treble. Jean Poulin is correct.

Uh, reminds me of a quiz show where two contestants were so smart every show ended in a tie. Out of desperation the host chose to let the contestants ask each other questions. The first question was how could a gopher made a burrow without leaving any mound of dirt at the top. The answer given was that the gopher started the burrow at the bottom, with the next question being "How did the little devil get there to start with?"

So how would the bridges move sideways? Well! It's the only direction they could move considering the angle of the strings across the bride pins!

Of course, you guys caught it right away.

Next question:
How much further do you think the plate would have to bend before it breaks?
[In the bass it's about 1¼" underneath the lid overhang while in the treble it is about ⅜" beyond the overhang. It's not a full-perimeter plate but like a grand (only reverse mirror image). So it's not just bending forward like some of the three-quarter plates do when the pinblock lets go from the back frame. Rather, the treble corner is bending forward and twisting towards the center.]

Ooooo, we get to find out? Might go viral on Youtube. Be sure to make it dramatic. Don't just put a chain fall on it. Maybe pull on it with a vintage tow truck driven by a buxom broad. Oh, Yeah!

I don't think it could go much further. It is surprising how much cast iron will bend.

I've only ever had a plate brake on me while restringing an upright. The pin block was not properly fitted to the flange so not the same situation as this piano. Scared the heck out of me, as loud as a gun shot.

I have seen this in an Everett studio from about 60 years ago. I have no idea how long it will last. If I were to try to fix it, I would remove tension in the treble and see if the plate bolts could be strengthened. But it is not worth trying, since I can find better quality pianos in better shape for free.

I've fixed a couple of these. Let off the tension, remove screws, drill holes, apply epoxy, install bolts, wait for epoxy to cure, bring up to pitch. Can be easier than finding another piano and then moving two pianos, one to the landfill with that cost involved.