Peter: Martin reluctantly owned up to me being the real owner of both my older models & did "guarantee" work on them, but it's been a mixed bag over the years; the last work they did is definitely not up to the standard. I was going to finally give the latest "CF" clone (think he's the 4th?) a piece of my mind - big time! - & list the many screw-ups his lads did; maybe send him a picture of the glue (or laquer?) piling up in front of the bridge after they finally replaced it. (The guys at the bluegrass jam think it's appalling; it certainly has not been good advertising for them to do such shoddy work..)
But my sweet midwestern wife brow-beat me out of it, at least partly on the reasoning that I will continue to own these guitars a long time (hopefully!) & may need their good will -ie, don't piss off the workers. Maybe CF would want to know - maybe he wouldn't.. ??? Don't know how to call it. (Could he do anything, any-way??) But I do know that a little over 2 years back I bought a new Martin from Rockin' Robin in houston. I have not yet sent in the ownership papers. (My sister died, we moved, they were lost in the clutter for a while, etc, etc..) Now, clearly I feel ambivalent.
Anyway, for all my other guitars except the "lifetime guaranteed" Martins, I have always done my own work; I'm a a sort of luthiery hobiest & sometimes work on my friend's instruments. Excepting the so-called guarantee, I would NEVER even consider sending anything to the Martin factory any more. Years ago they were great. I'm rather doubtful if they care any more, maybe they are too corporate now, & we who buy & play are just a means to an end. the stock market is what counts?
I do get a clear feeling that if you are a well known star, you'll be treated well.
Anyway: if they've shafted you out of your guarantee, at least they might've inadvertantly done you a sort of backwards favor. As has been mentioned by others, take your guitar to someone motivated to do good work. And next time, buy something else, like a Taylor.
Cheers & Good Luck, BK