Examine the rug to determine the extent of the damage. Look for tears, fraying edges or worn backings that cause the rug to slip. Determine whether you are capable of fixing the rug, whether it should go to a professional, or be replaced.
Measure and cut the replacement backing to fit the size of the rug if this element needs to be replaced. Turn the rug over and apply hot glue to the left edge of the rubber backing, pressing it firmly into the rug back. Moving your way to the right in a slow, smooth fashion of applying glue and pressing the new backing flat.
Thread the upholstery needle with the linen thread if you need to repair frays or a tear. Use a thread color that matches the wool rug fibers.
Run a seam with the upholstery thread across a frayed edge, creating a new thread barrier to prevent the fray from running farther. You may also run a new seam along the border of the new rubber backing to further secure it in place.
Cut a line parallel to a tear of the rug, extending your snip just past the edge of the tear on both sides. Overlap the new edges and sew them together with the linen thread. Keep stitches close together and tight to draw the two sides as close together as possible.