I have this Pedulla-Orsini bass that`s in near mint condition except (naturally) the end of one of the truss rods broke and some point and somebody dug down into the wood to find enough thread to save the neck. Trouble is there wasn`t enough thread left to straighten the neck. Anyway with the fingerboard off you can see that when the rod was originally installed both rods and anchor channels were back filled with putty or wood filler so that the surface of the neck was all smoothed and flat before the fingerboard was glued on. I`m not a luthier and I haven`t seen this before so I`m wondering what sort of filler I would need to re- do the neck (or if I even need to refill it at all). Also, It looks like I`ll need to replace about 1/2 " of missing wood up around the adjustment nuts (assuming I can find truss rods to fit). I thought about converting this to a single truss rod by removing the wood between the 2 channels but I`m afraid it might weaken the neck. Any help is welcome...Thanks!