I've noticed that some bridge pickups aren't quite square on the caddy which my OCD finds hard to deal with (pic attached). How is the bridge pickup attached to the baseplate and is it an easy job to straighten it up?

Easier to buy a new one. But the problem will go away if you don't keep looking at it.

Just carefully unscrew the bobbin from the back a bit and gently position it straight. Then, while holding it, re-tension the screws. Viola. Be very careful, as you don't want to damage the very delicate wires. I had to do this on my old 2017 4003.

QC is much, much better on 2020+ Rickenbackers.

_________________
https://soundcloud.com/koshchei-1