i havent did it yet, when i had mine apart cleaning it i didnt have any fishing line. id imagine any size within reason is ok, the rc thread the guy used 8# but the maast thread shows the guy used 6# with very similar results. the needlewheel is simple to take apart. look at the pics, looks like both examples have 3 revolutions of the fish line. just tie the line around one of the needles to start, then weave the line around, looks like inside out would be more efficient, then tie then line off on another needle when finished.