Pick up a tension bar, which is a thin metal bar that is used to attach chain link fencing to posts. Turn it vertically and walk to a location 5 feet away from the fence end where it is loosest.
Insert the tension bar into the top of the chain link fence and thread it down through the wires until it reaches the bottom of the fence.
Clamp the hook at the end of one of the chains, called a shackle, around the tension bar one-third of the way from the top. Repeat to attach another chain to the bottom of the tension bar one-third of the way from the bottom of the bar.
Attach the free ends of the chain to the come-along winch.
Turn the come-along winch horizontally and insert the hook on the other end around the center of the end post.
Cut all of the aluminum tie wires that connect the fence to the post using bolt cutters. Walk to the nearest post on the other side of the saggy area and cut the ties off of this post as well. Then cut off all of the ties from the top rail of the saggy area so the fence section is completely free.
Grasp the center handle of the come-along winch with both hands and push it toward the end post using firm pressure. Release the handle and it will go back to the original position. Continue pushing the handle toward the post until the chain link fence is tightened properly.
Insert another tension bar at the end of the fence where it meets the post using the same method as before. Attach the tension bar to the post by wrapping aluminum wire ties around it at 12-inch intervals all the way down the post. Attach additional wires along the top rail using the same method. Use pliers to bend and wrap the wires.
Cut off the excess loose chain link fence material using the bolt cutters. Unhook the come-along winch and remove the original tension bar on which the winch was attached.