[hoseman]

I've done it and it's not hard. First take off the lower handle deal (on mine there were two screws), pull the handle out and the broken rope will come with it. Measure the length from the handle to the top pulley, double that length then add about 18 inches, then go to a hardware store/Home Depot/Lowes and buy a new rope. Has to be non stretch rope) take the old rope with you to match the diameter - ask their guy to help you in "hardware".
Push new rope into top pulley, heading it down to the opening where the handle was removed. Coat hanger hook or something to grap the rope inside the pole and pull it out. Remove all remnants of the old rope off the handle as well the umbrella "slider". Tie new rope onto handle, then with the umbrella down, tie the rope to the umbrella "slider" (the "slider" is the deal where all the umbrella spokes come together at that plastic round thing that rides up and down the pole).
Reinstall the handle and go grab a glass of wine and enjoy your handy and inexpensive repair job.