There really is not a simple way to replace the rope on that model as a fair bit of disassembly is required to get to the recoil/starter assembly. In addition, there are also some safety considerations since the spring is under a fair bit of force and is thin enough metal to cut, so you may want to consider consulting a professional.
If you do want to attempt the repair, checking the exploded-view type parts diagrams on the Sears parts site might help. They will not show any specific repair or provide instructions but these are the same part lists and diagrams technicians use to aid in repairs and with careful review you should see the parts involved and roughly how they fit and work together.
To get to the Parts site, go to
or go directly to
and then type in your model number on the parts page. Select
and then choose your model from the search results. Use the
View Parts List
options for the various Product Sections to open the diagrams or parts lists.