12-string Taylor has run out of truss rod adjustment
 

What to do? I have a 12-string Taylor, about 22 years old. The neck has bowed (lower at 1st fret, higher at 12th fret), and the truss rod has no more room to adjust. It's still playable at the first five frets and to some degree at the upper frets, but I would like to flatten the neck, if possible. Is there anything that can be done? I've Googled this and found nothing practical. The guitar sounds good, still.
I've set it a full step lower (to D instead of E). Among other things, I am afraid that it will bow even further and then become unplayable. There is not a single turn left in the truss rod in that if I go any further the nut will come off.
I don't have much experience repairing or adjusting guitars, but there is no one around here who can do it (I live in China and can't go to Hong Kong because of the Covid-19 situation).

Taylor necks even the old non removeable ones are pretty good.

First establish if its a neck to body geometry issue or relief issue.

If you loosen all the strings off can you adjust the neck vee the truss rod so a ruler sits perfectly flat across the top of the frets, if yes can you adjust it a little further so the ruler now rocks on top of the frets?

Steve

Before I put the strings on, I could get the neck to flat. But after the strings went on, it bowed. Then I adjusted the truss rod to flatten it out but it can't go far enough. The nut comes off.

I’m not certain if I’m understanding what you’re saying, but, if I do, I think you’re turning the truss rod nut in the wrong direction.

You say you can get it flat with no string tension, but it bows with string tension.

You then say that you try to flatten the neck with the truss rod but the nut almost comes off.

If the neck was flat without string tension, adding string tension will cause the neck to bow forward.

To adjust against forward bow, you need to tighten the truss rod, not loosen it as it seems you have been doing.

So try turning the nut in the other direction bit by bit and see what happens...

sounds like you're loosening the truss rod. The nut should not come off when tightening it to compensate for string tension

Sounds as though, as others are saying, you’re loosening the rod when you need to tighten it.

Remember the rule when cranking on the adjuster - lefty loosey, righty tighty!

The usual disclaimers apply......IMHO, YMMV etc.

My advice: take it to a pro.