I just did this a couple weeks ago and had dreaded the process for years. Turns out it was easy. It took about 30 minutes. Here's the process I followed.....
1- Purchase 15 feet of 1/2" yacht braid. This is more than you'll need, but better to cut off the excess later. Also, the manual says to use 3/8", which I did, even though what I replaced was 1/2". I wish I had stayed with the 1/2".
1a- oops I forgot to add this one. Look under the cabin table where the compression post enters the base at the floor. Open that up and you'll see a large bolt. You will need a ratchet wrench that fits that bolt and can make the depth that you'll have to work with. Remove the gob of 5200 from the bolt.
2- You'll need to put the boat up 6' on a travellift. You'll go on the boat. Have at least 2 helpers on the ground.
3- when the boat is up, lower the centerboard and rest the lowest edge on a board.
4- cut the old line from the lowering rig from above. DO NOT LET IT GO.
5- sew, with heavy thread, the end of the old to the end of the new. Wrap it with one layer of masking tape. Make sure it is very secure.
6- Have your helpers hold the centerboard while you go down into the cabin and remove the bolt under the table. The bolt holds the centerboard assembly in the trunk. As you loosen the bolt, your helpers will lower the board to the ground.
7- When you have removed the bolt and the board is out, feed the line though, top to bottom and attach to the board as the old one comes off. It will probably need to be cut.
8- After the line is attached, have your helpers lift the board back up to the boat as you take in the slack. Then go back below and replace the bolt. The helpers will have to get the top of board all the way all the way up to meet the bolt. Tighten that baby up.
9- This is the part that was a bit tedious. After the board is reattached, you re-tie the uphaul to the lowering rig. I had to do it a couple time with a guy down there telling me that I had the board all the way up and that it was properly tied. It took me 3-4 tries. No biggee.
When you have it set right, you're ready to launch. It really was very very easy, especially compared to what I expected. The key was to have it up on the lift and have the helpers. Luckily the guys in my boat yard are great guys and were happy to help me do this on launch day.
Good luck!