musiclover:

There's a guy at the Larrivée forums (www.larriveeforum.com) who goes by username 'Sneaky'. He lives in Japan. He has acquired countless Yamaha classical guitars for dirt cheap, and has likely seen whatever issue you are pointing to on that specific model of guitar and would likely respond to a PM if you have photos.

He might even be able to answer your neck swap question.

Some of the FG series from that era ARE desirable, if I recall Sneaky's many posts on the topic. (He is always sending shots of his latest score in the forum).

-Scott