Mando neck pulling up advice needed

[Vernon Hughes]

Howdy all,
I recently (within the last few months) repaired this mando built by a respected luthier. He'll remain nameless. The neck was coming apart at the seam at the back pretty bad so I removed the fingerboard and neck and found a very poor dovetail, ill fitting to say the least.Action was super high as a result. I added wood to the dovetail cheeks and end to fill the voids in the neck block and chalk fitted the dovetail/neck back in place properly. Hot hide glued,fingerboard back on and touched up..all was well. Held tension and pitch for a couple weeks and I sent it back to the owner. Two months passed and I get a call saying its doing it again. Just removed the fingerboard to see what gives and all looks tight as I had repaired. Obvious crack at the back button seam and won't hold pitch.I don't do dovetails this way and haven't seen one done this way either. All that seems to hold the neck on is the smallest taper of the joint and where the neck sides meet the mando sides. I can stress it by hand even though it's glued tight.The truss rod is another issue,seems to be in a straight depth channel barely under the surface of the "meat" under the fingerboard. I've stared at this all morning wondering what action to take next.The fingerboard extension offers no support or bearing for the upwards pull of the neck that I can see. I thought of removing the truss rod all together and fitting another fingerboard extension that may offer some bearing and then install a CF bar or 2 along the entire length..Thoughts anyone?

[fscotte]

Send the pics to the builder. Maybe he can offer some insight.