I'm just doing mine right now. What follows refers to the earlier folding hoist model Rotary 42, not the fixed wire line models, or the current Hills folding hoists with this type line anchorhttp://www.breezedryer.com/index.php?p=product&id=791
I found that Hills don't sell new line direct, so I got some poly core line from Mitre 10, 60m for $30.
Study how the original line was strung through the clips and how it was tied at each end, and you will find that you have to remove 4 plastic wedges which secure the line in the end caps, these thingshttp://www.breezedryer.com/index.php?p=product&id=792
The wedge is not shown. You just push it out upwards. Then cut away and pull out the old line from all the clips, these thingshttp://www.breezedryer.com/index.php?p=product&id=741
Then tie the line onto one end cap as it was before, and restring the whole hoist. To get the line into the clips, you can carefully lever a bit with a screwdriver.
Don't worry too much about tension yet, just leave the line a bit slack on each run. You will have to pass the coil of line over the top of the arms many times. Finally cut it off after the final run, leaving enough line hanging down to secure the arms in a bunch when the hoist is folded up.
Make the final knot as it was, and then, without skewing the arms sideways, remove any slack going around and outwards, and finally pull in and tighten the final knot at the outer end, and replace the 4 wedges.
The line will stretch, so you may need this final step once more.