3below

Spot on, Firebass 700, built like a tank (personal experience) and from memory needed 2 Ohms to deliver the full 700W. I gave mine away as a bonus gift with the VBA 400 I sold.

Depends on what you are doing with the headstock and which end the adjuster is going to be at. I feel this approach will be much easier than chiselling / plough planing a channel

With some careful thought and measurement a thin strip of a suitable thickness down the middle can have the truss rod slot cut into it before gluing. This is something I intend to try - one day when I get around to it. Decisions, decisions. Following earlier comments, the G&L bi-cut neck was not a symmetrical split, the channel was routed on one side only. The joins are so well done they are very hard to detect on my two G&Ls.

G&L used to do a curved channel in the two neck halves and then glue it up with the rod inside. I only know this as I have a G&L from that era. https://glguitars.com/non-compression-truss-rod/ . I am led to believe that some Peavey and Hamer basses used the same method. The (very, very beaten) Peavey Patriot bass I have has a two part neck that suggests this is the case.

If you are going to make the truss rod channel by hand (plough plane, chisel, drill) then your rebate idea would help (to my way of thinking). As @Andyjr1515says there will still be tidying up.

Life intervened, in 2017 I started getting divorced after 37.5 years of marriage. Six years later it is only just getting finished despite going to court. Anyway, the bass still exists, the blunders were rectified and the neck has been perfectly stable. I would happily use oak again in some laminated form.

Owning a Kramer DMZ4001, I will echo @Shaggy's comment - seriously good basses. Since there is no (simple diy) neck relief adjustment a definite try before buying bass.

Very cool looking bass and great wood chops

A really good summary. Does the bass sing unplugged is an important one for me. I have been heavily using my Corvette fretless on a daily basis for the last 4 months and it has really opened up in this respect in the last few weeks. No idea why this would be with a solid body bass, if you had asked me that several months ago I would have not believed it possible. Stating the obvious, really unlikely random parts can produce staggeringly good results. One of the best P basses I have ever played was put together by a teaching assistant for a special school music room. It had been hammered in the time I I knew it. Made with a Peavey neck, unknown body, BBOT bridge and a cheap Chinese pickup. It was seriously good, it had the 'sings unplugged' factor in spades. An absolute banger of a bass, as good as anything USA I own.

The bad news is that when you have healed and things are good it is all too easy to trigger it again. Last time for me was passing someone a laptop one handed at arms length, stupidity on my part.

Great review, and yes, wood is expensive now

It is fixable, it is not going to be cheap if you pay someone to do it. My guess would be that a (used) replacement neck might be cheaper. If it is any consolation I stuffed my USA G&L L1505 neck with the truss rod cracking the fretboard (not uncommon I am told). Fixed to better than new by Jon Shuker. You could ask @Andyjr1515 what his take is.

Is there a melody / vocal line? If so it might help. @Waddo Soqable @Doddy & @Baloney Balderdash have the way forward. Put a recording on here, get more bass line ideas than you can shake a stick at

75 P bass, gorgeous ash body and a sane mass ✴️. In my guitar playing era I had a rather nice 1980s ash / maple strat (the body would be custom shop stuff these days). 9lb it was not, way too heavy, so moved on for another G&L bass.

£20 to get your bass ( and any other kit over a year ) advertised to the largest UK pool of bass players. Bargain in anyone's money. I looked at the kit I used on Friday's gig: bass, pickups, straplocks, machine heads, strings, sansamp, tuner and cab. All BC purchases

First outing with new (to me) prog Jazz rock band - all originals. A good evening out with a small but appreciative audience. The usual game of keeping the blunders as well hidden as possible, which for the first time out in this line up we did well. You can just see how we contained our drummer :), the eagle eyed will spot the Barefaced cab - Dubster being used with a fretless Warwick I had forgotten the joys of loading kit into the car, have an early meal, leave home at 5, drive for an hour, setup, play 2hrs +, pack kit up, drive home and sleep..... How did I ever do this when I had to work for a living as well.

Without the schematic this seems the only way forward.

That is the sort of tech you need, I know that feeling of 'not going to let this one beat me'. I look forward to hearing what the cause of these failures finally resolves to.