ikay

Lace Ultra Slim? - https://www.thomann.de/gb/lace_pickups_ultra_slim_bass_pickup_usab.htm Or a Shadow NanoMag - https://shadowelectronics.com/products/shadow-nanomag-pickup The Epiphone Zenith bass has a NanoMag fitted at the end of the fingerboard - http://www.epiphone.com/Products/Bass/Zenith.aspx

I think the only preamp that will give you everything you need is the John EAst UNI-PRE: http://www.east-uk.com/pdf/uni-pre-features.pdf This gives you active/passive switching (the active path has an active blend and passive path has a passive blend) and the bass, mid and treble controls all have adjustable frequency centres so you can tweak to your taste.

What don't you like about the stock preamp in the VM4? Knowing that might help with suggestions for a replacement.

Here's one with £1.75 postage - https://www.bitsbox.co.uk/index.php?main_page=product_info&cPath=225_226_293&products_id=3109

Hard to see from the pic. Is there a spare lug on the output jack (with solder on it) where it looks like it might have come adrift?

Yes DPDT on-on is what you need

The Ric wiring diagram for 2 pickups with 5 knob and mono output is here - http://www.rickenbacker.com/pdfs/19511.pdf This is the equivalent wiring for your 4005 copy. And here's a modified diagram with an added series/parallel switch (modified wiring marked in red). When switched to 'parallel' the bass will function as it does now. When switched to 'series', the two pickups will be in series and only the bass (neck) volume and tone control will work. The existing 3-way switch will need to be set to the bass (neck) pickup for series mode to function.

Looks great. I think I'll get one of these and consign my Fender bag to dust cover duties!

One for sale here in Croatia for 740 Euros https://www.njuskalo.hr/bas-gitare/yamaha-bex-bs-bass-bas-gitara-poluakusticna-magenta-boja-oglas-22180711

Bananas! https://www.webmd.com/pain-management/ss/slideshow-muscle-cramps-foods

https://www.talkbass.com/threads/defretting-graphite-neck-tuning-into-lined-fretless.681329/

According to the Hipshot dimensions schematic (link below) the main gear housing (the bit with the cog) is the same for all USA ultralite versions so in theory it should be possible to interchange the key/shaft/worm component. The different keys are shown on the second page. https://cdn.shopify.com/s/files/1/1574/0577/files/206.PDF?5066948558007359183 Note that the USA model has different dimensions to the Licensed model so you won't be able to swap components between the two. Dimensions for the Licensed model are here: https://cdn.shopify.com/s/files/1/1574/0577/files/206K.PDF?147414096911308745

D'Addario EXL170M medium scale set should do the job https://www.amazon.co.uk/DAddario-EXL170M-Regular-045-100-Electric/dp/B000OR2V74

I found this pic of a BP1 board on the Statii forum which shows the middle pin of the tone pot connected to one of the outer pins of the blend pot. The other pin of the tone pot isn't connected to anything. Here's the link to the thread - http://www.statii.com/forum/print.php?type=F&thread=2232

I did think of trying a shim on mine when I first got it. I removed the bolts but the neck was such a super tight fit in the pocket I decided to leave well alone. I think the tight fit of the neck is part of what makes it feel and sound so alive. The bridge is also tightly bonded into a recess in the body so energy transfer is maxed at all points.

String heights at 12th fret for my RA Mouse are: G - 7/64" (2.78mm) E - 10/64 (3.97mm) I have mine set up with an almost dead straight neck (just the tiniest clack of relief) so there's no further lowering possible on that front. The stock saddle is already quite low profile with just 4/64 (1.58mm) being above the saddle. You could probably lower this by 1mm max but it may affect string pressure on the piezo. Personally I wouldn't do that as there's really not enough leeway to play with. The Mouse really doesn't allow for a super low set up. On the other hand, the medium/high stock setup is optimised to allow a great dynamic range - and boy this diminutive little beast really does sing! The whole instrument feels alive in your hands, it's like no other bass I've ever played. I actually prefer a medium/low setup on my regular basses, but the higher action on the Mouse doesn't bother me at all. The nylon strings are very compliant and easy to play. The higher action allows them room to vibrate freely which lends an incredibly expressive character to the sound. Couple of pics below

According to this TB thread, a good rule of thumb is to treat the Epi 310 as if it was a 4 ohm cab: - https://www.talkbass.com/threads/epifani-ul2-310-ohms.1313100/ Set your amp to 4 ohms and it will be fine with a cab that's rated at 4 ohms or above (but not below) so will be ok with the epi.

Ibanez PCBE12MH (32") - https://www.pmtonline.co.uk/ibanez-pcbe12mh-opn-acoustic-bass-guitar-natural

Limited Edition I see, hope there are enough to go round!