"Take off the top nut on start
"Take off the top nut on starter, then the center screw and carefully remove the line disk.(remove rope handle fist)
Remove the old spring remains. Watch out, it gets looong.
Take the new spring, hold it tightly and cut the steel band that holds it together. Let it out in full length.
Put the housing up-side down. It helps if You may fix one of the 'legs' in a vice so it is stable.
Then start coiling the new spring into the housing, be sure it seats all way down.
When finished, have a new rope on the rope disk, and plavce the rope disk into the housing. Be sure to get the pin on the disk into the inner eye of the spring, and remember all nylon washers etc.
Tighten the center screw so no play is there, but not as hard so the line disk sticks. Watch out so the center bushing notches fits into the corresponding in the housing. Then tighten the top counter nut.
Good luck, You might want to use protective goggles and gloves, and keep wife and children away!"