While doing so...noticed that ribs 2-4 had an angle cut (as seen in 6W6 cutout detail (very center of page). Ribs 1,5,6 all had the straight cuts. This forced a flex in the rib in order to get it into place. I emailed Roger at Zenith for advice. "Do i trim it like 2-4 or reshape the rib with a mallet and wood block.