I finally replaced the Astrodome. And to anyone out there about to do this, don't worry. It went fairly easy.
First i removed the T-handles from the cranks (they just pulled off) Used a screwdriver to pop out cranks, and removed the screen. Then i removed old Astrodome and placed on the table. After measuring old Astrodome and marking drill points on replacement Astrodome, i drilled and riveted the old cranks to it. I also cleaned and lubricated cranks. Then replaced Astrodome in opening. Success!
I am very happy with the replacement. Thanks to everyone who chimed in.