What is an easy way to wind the spring for the

Be careful to much pretension can break the recoil spring. Just one additional turn at a time is what I recommend. HTH
Lou

if you set the spool down into the case and have the springs attached to the case and the other end to the spool but the rope shouldn't be totally wrapped around the spool. Leave about 8 inches of rope where you can grasp it. There is a small slot cut in the spool where the rope coming from the spool can ride it. That will let you wind the spool tighter and tighter. When you have about 5 or 6 turns of the spool, position the slot in the spool even with where the pull rope enters the case. Pull the excess 8 inches of rope back out through the slot till all the rope is outside the case or wrapped on teh spool. It should now wind it all back in. You might have to adjust the 5 or 6 turns of the spool as different saws have different lengths of rope and different size springs.