Paul,Are your sail panels original? If they are original the top edge with the rib is held on with push in clips ( probably 3 of them). The bottom edge of each sail panel is held in place with a curved painted pieces that are pushed down onto the package tray. The original sail panels might have been stapled to the body using cardboard strips attached to the metal body.
Reproduction sail panels cardboard do not have the slots for the upper push in clips.
I have to add the slots to my reproduction sail panels.