Finding a high Fret:
Be very sure that the fret is completely seated in the fret slot before doing any kind of filing or sanding.
Loosen the strings and tie them back off the fretboard, no need to remove the strings if they are good strings.
Using the truss rod adjust the neck perfectly flat, if you do not do this the fret rocker cannot give a correct read. I know, the other guys never mention this, shame on them.
A Fret Rocker is a crude 19th century tool based on an ancient masonry tool. It looks so simple that most people never learn how to use it correctly.
Span only 3 frets, the idea is that the rocker will rock on a high fret that is the middle of the 3 frets, but this is not always the case, it can also rock when two side by side frets are high and the 3rd fret is low... pay attention. And again, the other guys never mention this... shame on them.
When you find a high middle fret Never reference that fret to check other frets, that means do not move the rocker over one fret to bridge the next 3, it will not read true because you are referencing a found high fret. I know, all the videos you may have watched never tell you this... all I can say is, shame on them.
Mark the found high fret with a sharpie.
Select one of the four sides of FretFixxer that spans only 3 frets, center the file atop the fret, file in straight even strokes and NEVER jam down on the file because you will ruin the file, and that includes any and all fret files no matter who makes them.
Nickel frets typically take a few minutes.
Stainless steel frets take 6 minutes or longer because stainless is many times harder than nickel.
Use the weight of the file and only light pressure. Light pressure allows the sensitivity required to know when the fret is leveled. Heavy pressure does not, and you could over file which at the same time means you are gouging the reference frets on the left and right.
This is true of all spot level files, and yeah, the other guys never warn you, they are afraid if they do that you will think their tools is hard to use, so they let you get in trouble instead and then shamelessly blame you when you ruin your frets.
If you are not sure about the progress, use the rocker to check. The old saying "Better safe than sorry".
FretFixxer leaves the fret about .0003" tall so that when using 600 to 1,200 sandpaper to smooth and polish the fret you do not sand the fret to short.
FretFixxer is not a fret rocker, do not use it as one.
The Optional Handle:
Most people prefer not to use the handle.
Watch the video, that is the easiest way to know how to use the handle.