Hi PShilling.
I found on my FVB-4 kit that the strings on the nut were really high. I removed the nut and sanded down the base rather than filing down the string slots (since I don't have slot files yet). I did need to file down one slot as it was a lot higher than the others.

To check for the appropriate height: I use a small straight edge (metal ruler) and rest it between a string slot and the second fret so that the heights above the first fret are about:
0.10 mm for G
0.15 mm for D
0.20 for A
& 0.25 for E.
Similar values can be found online. Another member (cannot remember who) said they put the string slots to the same height as the frets! I'm sure there are other methods out there. I'm not sure which is best.

I did a similar thing for my FBM-1, of course with different heights for a 6 string.