MIMF

Back in 2000, I made an impulse buy of a '67 Gibson ES335 TD12 guitar off ebay. When it arrived and I first played it, I knew it didn't play well but I wound up keeping it anyway. Several trips to one shop for tweaks have proven the problems go beyond correction from the truss rod as the shop put a couple of washers under the truss nut to try to get a bit more out of it. It's playable but...challenging. It's in great shape cosmetically (w/original case) and sounds great.

Over the last few years I've heard a lot of good things about another local repair shop so last week, I brought in the ES12. He found it has a slight neck twist (which I had missed seeing) but was impressed by the guitar and thinks he can get it back into shape by heating and clamping the neck. The last shop said he thought the next course of action would be to plane the board and refret.

The problems I'm aware of are 1) even with the max'd truss rod adjustment, the neck still has a bow and 2) there's a bit of a twist to the treble side. I can see the twist by sighting down the neck and comparing the headstock to the upper bought but the board, to me anyway, doesn't seem twisted (perhaps I just can't see it).

While the guitar is playable, the bow causes fretting to pull it out of tune in most positions. I would like to restore this guitar's playability if reasonably possible without destroying it. Some on other forums have suggested all sorts drastic actions such as converting it to a 6-string but that's not what I want to do.

What would you experienced repair people do if this was your (or your customer's) guitar? Can heating/clamping successfully correct the neck bow and twist AND will it last? Is planing/refretting to compensate for the twist a better way to go?

I never like to trust the heating of warped necks. I feel it doesn't last, and it also has to be perfectly done or all kinds of bad things can happen, like melting of the finish and so on.
I would go the further route and have it planed and re-fretted. If that's done right it'll solve all the troubles.

The first thing I'd do is tune it down two half-steps and see if that helps. It probably won't solve your problem, but it might help, and it's free. I've always tuned 12s down two halfs. The heating/straightening has been discussed here several times, and seems to have no better than a 50/50 chance of working, and even less chance of lasting. Planeing and refretting, or maybe compression fretting would be better options.