Clamp the Husqvarna chainsaw in a vise, or set it on a work table, with the bar away from you. Take note of a distinctive mark on the chain, or draw one with a permanent marker.
Rest the chainsaw file on one of the teeth on the left side of the chain, angled to the left over the top of the chain. Match the angle of the file with the existing angle in the tooth. Slide the file forward four times, while firmly pressing down and away from the end of the bar. (Do not change the angle as you file.)
Repeat filing with all the teeth on the left side of the chain, rotating the chain as needed. Stop when you reach the beginning mark.
Angle the bar of the chainsaw to the left, to better access the teeth on the right side of the chain. Rest the chainsaw file on one of the teeth on the right side of the chain, angled to the right over the top of the chain. Match the angle of the file with the existing angle in the tooth. Slide the file forward four times, while firmly pressing down and away from the end of the bar.
Repeat filing with all the teeth on the right side of the chain, rotating the chain as needed. Stop when you research the beginning mark.
Check the depth of the gauges (on the chain between the teeth) with a Husqvarna depth gauge tool. File the gauge down with a flat file, if necessary, to match the depth gauge tool.