Switch, welcome to the forum - sorry to hear of your cable failure. The cable routing diagram is in your owner's manual and it's the only "diagram" I know of. Looks like you found this writeup: https://www.hilotrailerforum.com/f22...djustment-125/
and that's the "bible". There has been very little change in the lift system through the years, so what worked to repair it 40 years ago still works now.
From your post, is sounds like the cable broke near the upper pulley on the top half of the trailer. This is the place where it seems to always break and is the part that needs annual inspection. You have to take the trim strip off the inside upper half to see those pulleys and the cable going over them. This is when you apply a lubricant that will soak down the cable on both sides of the pulley too.
I've not replaced a cable, but I would think you feed the new cable down both sides of this upper pulley too, when putting in a new one. Once the cable is down to the underside of the trailer, you can feed it around all the pulleys under there and out to the frame. Get the bolt through the frame and put a nut on it just far enough to secure it. Then, get the cable stretched as much as you can before securing it to the top half. It will be impossible to remove all the slack in the cable, so you'll need as much shortening capacity at the adjusting bolt as possible, to finish the installation.