Mark - in the fret levelling video you use a sharpening stone - what grade/grit do you use - any idea of where you got yours?
Measure once........ Measure again......... Sod it - make tea!
Hey Bill! Good Q. Mine is 300g and from Tonetech :
https://tonetechluthiersupplies.co.uk/diamond-fret-levelling-file.html
The main reason I suggest a sharpening stone is because you may already have one in the shed.
If not it is a little expensive to buy just for the leveling the frets - but the Tonetech is especially good as it is larger than average, wide enough easily to sharpen a plane and appears to last extremely well.
...or...You can make your own with any flat block and 300g sandpaper for 1 time single use.
Measure twice, cut once...