Just have a go at trouble-shooting yourself, if you have a multi meter then use it to check the pickup resistance.
Something may be shorting to the shielding so have a look for that
That really depends on the strength of the neck, maybe try tuning each string up half a step or so at an evening and then tune it back and see how that helps the relief. The extra tension might just shift everything back into place
This is the closest i can find on ebay, https://www.ebay.co.uk/itm/Jazz-Bass-Electric-Guitar-Body-2-Piece-USA-Alder-Black-Gloss/401312056054?epid=2016453414&hash=item5d701002f6:g:J8AAAOSwzaJYAAMW
Thats a fair point. I think the main issue regarding starting out luthiers is that nowdays people go for a cort or chowny instead. I really admire companies like this as they are able to produce amazing instuments for a third of a price that i can. The issue with that is all of us are left here with not much buisness. I think in the next few years we will lots more people designing instruments but sourcing parts and labour abroad.
I think large companies such as cort or fender should fund research by luthiers. this would mean that the instruments could be manufactured on mass but be prototyped and designed by a smaller company/individual.