On mine there's a through bar at the top - one side of the cord is fastened tight to the bar. Then down to the rising boss and around one of its pulley wheels and back up to and around the fixed pulley wheel at the top and back down again - then a plain loop back up on the other side of the pole (no pulley wheel involved) through and around the fixed pulley at the top - down to the rising boss - around and through the pulley on the boss and back up to be tied fast at the top.
As I recall the re-stringing is best done with the parasol raised - I used nylon cord from a camping shop - burn the ends with a lighter to stop fraying.
Good luck...
Peccavi
April 2013
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