How can we contain the ribs, keep from falling out of the slots so we can line up

On the patio offset umbrella, How can we keep the 8 ribs from falling out of slots so we can put in the shorter ones, (second set)? The metal ring is open that threads the spokes. The rope seems to be intact.
This quest is driving me bonkers.

How can we contain the ribs, keep from falling out of the slots so we can line up