Turn the adjusting nut either way until there is less than an inch of play in the slack adjuster.
Turn the adjusting nut to move the end of the slack adjuster toward the air chamber until the nut stops rotating. Then turn the nut in the other direction to move the brake shoes away from inside the brake drum.
Turn the adjusting nut to move the end of the slack adjuster away from the air chamber as far as it will go. Then turn the nut in the other direction to move the brake shoes toward the inside of the brake cylinder.