As a lot of you I try to do most of the set up and repair work myself on a bass ,especially set up as to an extent its quiet personal to your playing style(bar neck relief, levelling ) I use roto rounds strings and they scratch the hell out of frets. I've tried the different grit fret rubbers that you can get which are ok but take a lot of time and work........but one of these fits the bill perfect  https://www.wilko.com/en-uk/wilko-nail-buffer-4-in-1/p/0348223....ideal for getting scratche