Knackered Yamaki 12 String

I arrived at the shop this morning to be met with this:



"Lovely" I thought to myself. "An MIJ 12 string by a builder known to produce top quality instruments." And this was the first one I had seen.
Rosewood sides and back, and a cedar top. An unusual combination.

The euphoria, however, was short lived. As I looked closer I saw this:










Yep, even with the crappy cell phone pix you're seeing correctly. The soundhole on the pick guard side had sunken a full 1/4" (6mm)!! And there is a corresponding crack on the opposite side next to the neck tray. I had a look inside with the mirror and all braces are solidly attached, so I have no explanation for why this happened, and only on one side!

A straight edge behind the bridge did not reveal the usual "hump". It was almost flat. Weird.

This was a beautiful guitar in its day. Made me tear up to see it in this condition.   
I restrung her and tuned it down a half step, and that was about all that could be done. I recommended that the owner drop it down at least a full step and then capo it up to pitch.

I used to yearn for one of these but every one seems to have major structural problems.

Really. Interesting to hear.
The only thing I can even remotely blame might be the bracing??
It seemed a tad on the light side, particularly for a 12 string.  

My thoughts and that's all these are -
Yamaki turned a beautifully made 6 string into a 12 string without changing the structural things they needed to.
Why? Because it probably sounded fab at the time so they went with it.
Ive seen a few for sale and they all seem to have structural problems or they have been kept, unplayed, with the strings loose.
Conclusion I came to is that they are not viable.

Sounds about right to me. What a shame.