Rick, I think the neck resets are mostly because any seventies Martin is now between 20 and 30 years old (Duhh!). I think a neck reset between 20 and 40 years old is a given.

What I understand is that a lot of seventies Martins have the bridge saddle just a little too far forward, or maybe back, in relation to the frets, so that they don't intonate right, especially if you play above first position (I'd be pretty safe).

I get the impression that Martin was on the way out until Chris IV took over just in time.

Peter.