Backwards bow after refretting
About two years ago I purchased a Yamaha BB3000 that had been defretted and had a preamp installed.
I had a luthier restore it to it's original state, remove the preamp and install new frets. He did an amazing job at it and the bass is/was a killer.
I was living in Iceland at the time, but moved shortly after that to Denmark, which has more humid climate. After a while I started noticing some string buzz which became worse as time progressed. Now it has gotten so bad that after having loosened the truss rod completely, the neck has a slight back bow around the 7-8th fret. Needless to say, the bass is completely unplayable now.
What I'm thinking is that the frets might be a bit too stiff and forcing the neck when the wood has soaked in the humidity here (still not so high, around 45 - 50%).
I would love to get some input from you, and hear your thoughts about this problem.