I'll give it a shot. The service manual is a simplistic view of the ladder rigging that is more complex than what it seems. It shows how the parts are arranged, but not how to accomplish it. You will need 3 things, a cold one, patience, and tweezers. I took apart one of mine to restring.
Picture one is the string with spring detached.
Picture 2 is with the spring removed from the line, feed it through the 4 rung from under-neigh.
Picture 3 is the small loop is fed through the larger loop.
Picture 4 and 5 draw line tight.
Picture 6 drape line over the plastic pulley. This is the weak link and snaps in two easily with age. Insert top ladder.
Picture 7 feed line on back of ladder to red turret..
Picture 8 Now this is where it gets a little difficult. You need to feed the line in the small narrow slot between the ladder rung and the pulley, you'll need your tweezers. Wrap 1 and 11/2 times around the winding pulley. then out the back part of the ladder in the rear slot.
Picture 9 shows how it should look.
Picture 10 shows ladders and line. This where you re-install the spring in the small loop and feed between the 2 ladders.
Picture 11, you will need your tweezers to feed the spring and line between the 2 ladders. Work from under side. The spring is stretched 2 ladder rungs past the relaxed position on the spring. This will give the line enough tension to grab the crank pulley to raise and lower the ladder.
Picture 12 bottom view. The crank should raise and lower the ladder. The ladder should extend about 4/5's of its length. If the winding pulley slips, you can add a slight bit of oil on the edges of the ladder that ride on each other to reduce friction.
I hope this helps. It's not a easy process. Good luck.