Severe Stingray buzz, looking for tips and suggestions

[SikSan]

Greetings!
Enlish is not my first language so I apologize in advance.
I own BFR MM SR5 all rosewood neck, which is my dream bass tone wise, but it has some serious issues I'm trying to resolve for several years already. The buzz is pretty strong even at moderately high action.
I've bought it used and I got kind of scammed, because the bass fretboard was warped, but I did not notice it myself until I went to a recommended luthier to set everything up properly.
He sanded down the fretboard, made a refret, but the buzz did not go away. The guy said he does not know why and rosewood neck is crap, blablabla. Fail #1
I tried to get over it since I was really in love with the instrument, but later I've made another attempt to fix it. So I went to another recommended luthier This guy said the first guy was an idiot and did not sand the fb enough. So he sanded it again, did a refret, reajusted the neck pocket, glued in a new nut (EB guys were kind enough to send me a couple of those nice patented nuts, cuz mine was damaged during the 1st repair ) and checked everything else, including the thruss rod.
The buzz did not go away and the guy said he does not know why. Fail #2

Fretboard surface is about to start chewing the fret markers after 2 shavings and action is about 3.5mm at B and 3mm at E currently which can't be considered low action, I believe.
I'm thinking about full fretboard replacement, but idk if that's a good idea and will it fix the issue.

[Stephen]

Hi SikSan!

Gongratulations on this rare BFR!

Internet diagnosis is not an easy thing to do, especially after the neck already went through two major "operations". I take it that you don't live in the USA, so sending the bass to EBMM Customer Service is not an option?

If so, it would be helpful if you provide some pictures, namely nut and first fret (parallel to the fretboard), bridge (same perspective) up and down the neck.

A truly warped neck is rare, but it happens. One way to diagnose this would be to play each string open and then each fret up the neck. Maybe prepare a piece of paper and mark the frets where the buzz is the strongest. There must be differences!

Do this with a staccato feel: medium attack and dampen.

If you find a lot of notes buzzing with staccato, try a second run and let them ring.

Let's take it from there.


Edit: All of the above is assuming that you play in standard tuning and with EB Slinkys. Also, the current setup should be reasonably even. I had most of my setup/buzz issues when trying out different strings (like dozens) - some needed no or minor adjustments, others took days to iron out.