Yeah I have seen that one. Really want to do that. But for now, even without sanding my bridge can’t go very low without getting buzzy or fret slapping strings. I know how to do a basic setup but on this one it doesn’t seem to work out somehow. And I don’t even want that low of an action.
So I’m hoping it’s the one thing that I can’t do myself: the nut.
Although I also have a slight fear that the neck may be a little off. Relief can differ from bass side to treble side, but on this one the difference seems bigger than I’m used to. Several mm’s.
In that case it might not be worth upgrading too much.
The nut won’t matter at all, these basses have a zero fret which nullifies the nut. All it does is provide a channel for the correct string spacing. Have you adjusted the truss rod as well? It’s a fickle instrument to setup, my pro luthier guy did “a setup” and it was like you described. I worked at it for a while adjust truss, re adjust string heights, bridge, etc. wait a couple days, do again. I’ve got it as low as it will go without fretting out or buzzing. My bridge is bottomed out on the e string side and just a little up on the G string side, if I hadn’t sanded the action would be a lot higher.