Bigguy2017

The body has a massive split with some very dodgy glue...

Yes, that's all original Fender Japan wiring.

The Neutrik website and catalogue are no help - they still have the discontinued models - very confusing. I've got a few NL4FX on hand, and they're still in stock with CPC / RS but if I need more it might have to be the newer ones NL4FXX 37 A 250 V AC NLT4FXX 30 A 250 V AC NLT4FXX-BAG 30 A 250 V AC

Even the Neutrik ones are different thicknesses - here's an NL2FC, an NL4FX, and an NL4FC. Weird....

Orchestras do this all the time...

You can wiggle a bit of pipe insulation over the left-hand arm bit - this helps offset basses sit level

The Palmer AHMCT8 one does Speakons - and it has probes + buzzer - very handy £46 inc P+P at Thomann https://www.thomann.de/gb/adam_hall_ahmct8.htm

Nice to see Gandalf doing a bit of sax work.

Using the 12th fret for measuring action height makes calculations for saddle height and neck angle easier. 1mm change at 12th equals 2mm adjustment at the bridge saddles.

They could all be on the same ring main

I'd try a with wiring check plug at Rehearsal room 1 - It may have a missing earth ;-(

Here's something https://www.talkbass.com/threads/ric-bass-wiring-diagrams.1218400/

Could be many things.... The way to approach it is to prep a cable with 1/4" jack (amp) to croc clips. Start with the pickups- unsolder at the pots and connect to the amp with the croc clips - how do they both sound? Next, wire pickup to a volume pot (disconnect tone pots) - does it still sound good - does the volume pot work as expected? Next connect the tone pots (one at a time) - do these work like tone pots? Next, the switch.... croc leads on the 'output' - do all three positions work as expected? If all is good then so far you have two working pickups, two working vol pots, two working tone pots and a working switch OR you will have found some problems to fix... Finally reconnect the output jacks - these are a flippin' nightmare on Rics with the whole Ric-O- Sound stereo / mono switching. It's often easier to fully rewire than try fixing previous dodgy fixes. I'm looking for a good Ric 4003 wiring diagram - best I could find is this... what you really want is a diagram with the parts and wiring shown as-is.

Bass -> Sgfx Beta-V -> Fender Rumble 200 combo -> Focusrite Scarlett 8i6 G3 -> Studio One Compression and EQ in the DAW

Those are 1/4" (Imperial) mini pots ?? Are they Alpha or CTS pots? nuts are either 1/4"-32 OR 1/4"-28 ? Anyone know for sure? The metric mini ones are M7 thread with a 9mm nut https://www.thonk.co.uk/shop/alpha-nuts-washers/ Full size pots/jacks such as CTS and Switchcraft = 3/8" x 32 thread. Full size metric pots such as Alpha = M8 x 0.75 thread.

Schaller, Gotoh, Hipshot - not much difference really

I've had good results with glass fibre tape + epoxy on the inside, then an epoxy / slurry crack fill on the outside. Sand off any lumpy bits and finish with Plastikote black satin rattle can.

Could be Planet Waves Custom Series... https://www.fnx.ch/en/shop/jack-planet-waves-custom-series-610m-3 but other that that obscure Swiss site I can find nowt more about it.

The sticker in the pickup cavity shows 1979

You'll have to get a replacement stacked pot. Lift the scratchplate and take some photos... is there a PCB or are they separate pots?

Lindy Fralin Jazz Bass set 5% overwound. Sound phenomenal on my MIJ 62 JB RI.

Yes, use one pickup only, vol and tone on max, phone about 4" above pickup, make sure the Toneprint is for your Amp - I use the Spectracomp in my BG250 combo.

You could wire the pots as variable resistors across the output. The volume pot would then give; from 250K load (like standard vol pot) to 1M25 load - could use a zero load pot here The tone pot would give; from standard tone at 100% to basically nothing - could use a zero load pot here too.

Simplest way is using an HDMI cable (IF your tablet can manage an HDMI output) - what tablet? what connections? If you can find an HDMI adapter for the tablet then a cable should work. With no HDMI out there is Miracast IF the projector supports this (which it probably won't) - what projector? You may be able to Miracast/Airplay (if tablet can( to a Miracast/HDMI adapter at the projector, but there's a lot of 'ifs' ... Something like this https://www.amazon.co.uk/AT-Mizhi-Wireless-HDMI-display-adapter-Black/dp/B08T22S76M/ref=sr_1_4?crid=3I37DXD9Z7PNG&keywords=miracast%2Badapter%2Bhdmi&qid=1686048719&sprefix=mirrorcast%2Badapter%2Bhdmi%2Caps%2C70&sr=8-4&th=1 A laptop with an HDMI out is much more likely to work.