Is your pull starter rope always breaking when you try to start your lawn mowers engine? Does it fray easily and then break?
Over time a pull starter can develop some sharp edges in the plastic or metal that the rope has to go through. These sharp edges will slice a little of the rope at a time and when enough of the cords are broken, then the rope will break.
You want to check the entire length of the pull cord beginning with the eyelet on the right side of the handles. Make sure that it is smooth and if not, some light sanding with some sandpaper will do the trick. Now check out the recoil starter itself for any nicks in the guides both on the plastic and the metal. You can smooth those out or you can replace the entire starter assembly.
Some engine such as Honda, have an easy 3 bolt system that holds the starter in place. Briggs and Stratton has a more complex system and you may have to drill out the old starter and bolt in a new one.
After you replace the starter, it should be good to go unless the rope begins to cut into the blower cover or guides one again.