Remove the front cover by firmly rotating counterclockwise. Pull the old line off the reel. Thread the new line through the front cover. Tie an arbor knot around the spool arbor and pull tight. Reattach the front cover.
Put tension on the line between your thumb and forefinger and slowly wind on line by pulling it off the filler spool. Periodically remove the front cover to see how much line has been spooled until the line is approximately 1/8" below the top of the spool.