An unhealthy neck can “get good”, and it doesn’t need a luthier. It just needs some common sense, and someone willing to learn a bit. (Within limits of course.)
I did it with a Squier CV Jazz. Otherwise great condition, but the neck was significantly warped and the trussrod nut was as cranked as possible. And it had fret sprout. So I got it for a fantastic price, more than low enough to justify purchasing a replacement neck.
But I went to work. Asked a few questions around here, did some other research. The steps I took:
A. Dig out the trussrod nut.
B. Create a ‘spacer’ to allow the threads more length to engage.
Doing that made the instrument playable. Not great, but not bad. The strings needed to be loosened after every playing session to keep the neck playable over time.
Next:
C. Heat-treated the neck. Not severe treatment, gentle. Some explanation is in order here. I reasoned that it’s possible this shipment, back when it was new, might have sat for too long in a shipping container under the heat of the sun or something. So I might as well try to reverse that! I have forced air heating, with one duct in my studio that blows nice hot air. I suspended the bass below that, with the body and headstock a couple inches above the floor. I put a wet Bona floor cleaning pad lengthwise under the neck, and put two 8-pound dumbbells on the most warped area of the neck.
I let that sit there for a week, during the coldest part of the winter when the heating system was on quite frequently. It had significant positive impact.
Today, I still loosen the strings when I’m done playing it. But it can go a couple days without that, and the action is now as good as I could imagine. It plays beautifully. Which brings me to the final treatment:
D. A fret filing block to correct the fret sprout. Yes, a mere mortal can do that job. You just need to be patient. The block does the major removal of edges, then you remove the file from the block and use the file to treat each fret end as suits you.
