Share 'Reinforcing 70s Martin Neck (Erlewine's Graphite Trick)'

Hello folks, first time posting here on the forum but I've learned tons from Frank's site as well as browsing the forums, thank you to everyone here for the perspective and information. I've got a 1977 D28 here in my shop for a neck reset among other things. It has the square non adjustable truss rod reinforcement common on Martins in the 70s. While watching Dan Erlewine's Advanced Fretting Vol.…