The guy I brought it to for a look see said it looks like they did not sand the bridge to the radius of the top. We all know a flat top is not flat.
I'm sure Martin knows that.
Don't want to slam Martin and I guess it is possible it was put together a little too quickly and not enough care was taken to match the bridge profile to the top profile, but to be fair tops are also known to distort under tension ("bellying") especially if strung with heavier than design-spec strings.
The 12er I knew was lifting just a bit on the back bass side corner (He told me to tuned down a half step and use a capo and watch it)
Easy for him to say if he's not the one playing it and you have my sympathy if you don't want to be stuck in "flat hell" or use a capo.
(I HATE capos if only because they take away frets from my favorite part of the fretboard, the bass end)
My best buddy's first-year JF30-12 also had some lift and after getting the warranty re-glue he went with silk and steels 1/2 step down (no capo) for many years , as a preventive measure against recurrence .
I didn't mind when I went to jam with him but I'm an oddball that way, I kinda dug it because it gave me an opportunity to play scales I wouldn't normally get to use.
When he got back in a band he went to
full step down, no capo.
If you also prefer to maintain a standard tuning but want to reduce tension on the bridge this might be a good time to look at silk and steels, which offer significantly lower tension as a set than comparable full metal sets.
I have a similar issue on the F65ce and Guild's own Authorized Repair Center at the time also told me to just wait and watch but never mentioned tuning down. (it's already spec'd for .010 extra-lights)
BTW it's been stable all that time, I made a template by tracing the bridge outline onto a piece of paper slipped under the back and corners, it'll help you "monitor deterioration", if any.
I thought of s'n'steels myself recently when actually looking to try to get a woodier tone out of it, went for silk'n'steel .011's and tuned a
whole step down and actually
loved the results, with very little volume sacrifice, and the added benefit of continued confidence in bridge stability.
But that's a thin top that responded well to lower tension.
Anyway, don't write off the experiment 'till you've tried it, if interested.
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