fret levelling is surprisingly easy, you just need a few essential tools.
1/ flat diamond coated sharpening stone, people used to use the stone ones, but these will wear after a couple of uses, only use the extra fine edge
2/ crowning file, again diamond coated, StewMac has some good ones, or go the traditional 3 corner file with the edges removed
3/ a fat chisel shape Sharpie/Marking pen
4/ a dremel with a buffing wheel and the fine white jewellers rouge..
5/ some of those stainless metal fret protectors that StewMac sells.
First make sure the neck has no twists or bows, adjust these out first.
then run a line over each fret, the chisel shaped marking pens are great, only one stroke required
now get your diamond sharpening stone (the longer these are the better) and proceed to run it up and down the neck in long strokes
you will soon see where the low frets are, as they will stil be covered in the marking pen..
also its not unusual for a particular fret to be high at one end and low at the other
keep stroking the diamond stone until all the frets are showing metal.
now.
remark the frets again with the marking pen
crown the frets using your preferred tools.
you should be left with a thin black line right through the centre of the fret.
now get your dremel and buff , and using the fret protector, apply rouge to the wheel, (dremel on full speed)
make sure you really get a lot of the rouge on.
start to buff.
the frets will shine up like new, and also remove the dressing marks left by the stone and the crowning file..
tip..
you need at least 2 of the protectors, leave one as nature intended, but cut the sides off the other with a sharp pair of tinsnips to use on the upper regesiter frets..
I'm sure there must be something on you tube or other media about this..
I learned a long time ago in a galaxy far, far away... before the interwebz..