In the 60s I had a japcrap 12-string guitar. A friend sat on it and snapped the neck. It was repaired, but never really recovered and over time the neck bowed. It didn't have an adjustable trussrod and it seemed the only thing to do was junk it. More recently, when I first started using eBay, I bought a Crucianelli 12-string, which turned out to have a nicely bowed neck and similarly lacking in the truss rod dept. Local luthier wouldn't touch it, so I put it back on eBay, with full disclosure. Someone in Canada bought it, for more than I paid, at a time when the exchange rate was totally in our favour. No idea what he did with it, or whether the enormous cost was worth it.