Re: How would you fix a headstock problem like this?
I'm no pro, but if I were to go further than gluing and clamping, for structural integrity I would probably consider a veneer or two before thinking about dowels. Perhaps a combination rear veneer/volute that extends along the headstock, thicker materierial between the tuner plates, maybe
Hereby & forthwith, any instrument with an odd number of strings shall be considered broken. With regard to mix levels, usually the best approach is treating the mandolin the same as a cowbell.