Remove the screws on starter housing cover, there are usually two to four, then remove the rewind starter from your Craftsman push lawn mower. Pull the old rope out of the starter pulley. Take the new cord and thread it through the hole in the pulley, tie a knot at the end of the cord, and use a lighter to melt the end of the nylon cord to prevent it from fraying. Next, wrap the starter cord counterclockwise around the starter pulley twice. Take the other end of the starter cord and thread it through the hole in the starter housing cover and reattach the pulley to the lawn mower. Fasten the starter housing cover screws and then try pulling the starter cord a couple of times. The starter cord should retract into the housing.
Most starter cord replacements come with a new handle, but if you just purchased new rope then you can use your old handle. Thread the cord through the handle and tie a knot at the end. You should melt the end of the nylon cord with a lighter to keep it from fraying.
You can find the model and serial numbers located on your Craftsman push or self-propelled lawnmower somewhere on the deck of the mower.
NOTE: if you need a part for the small engine in your Craftsman push or self-propelled lawnmower, there will be a separate model/serial number for the engine. Here are the small engines that are available in your Craftsman push or self-propelled mower. Visit the page of the engine you have to find out where the model/serial number is located for your small engine model: