Warped!
There are all sorts of ways to damage an instrument, and I’ve seen them all, I think.
No photo for this one–I’m just going to point you over to the first new article I’ve put up on my book site since 2012, an explanation of how I scan archings on violins with my carpenter’s laser.
I recently showed a violin getting a breast patch. Here’s a shot of that same top, prepared for making a plaster cast. The top has been spot tacked to a sheet of plywood, then a sheet of very thin latex stretched over it to protect it.
A few years ago I ran into a 3/4 cello with unusually strange top wood and now recently I’ve run into another, a 4/4. This is also an old Italian cello,
Usually tops and backs are just glued directly to the ribs and linings, nothing fancy. At various places and times in the past, though, sometimes makers locked the top and back in place.
Sometimes a violin’s arching is vulnerably flat, perhaps the wood is weak, or thin, or a combination of those, and the center under the bridge starts to collapse. Often this is accompanied by the top puffing up under the board and the tailpiece, towards the ends. In such a situation, the arching is first corrected back to the way it originally was made, and then