RTT Fabric Edge Fix Suggestions

So the edge of my CVT Mt. Shasta Pioneer Extended's canvas material has started to come out of the channel/slot that holds it to the base. I finally have the tent off the truck today to get this fixed, but I'm getting stumped on how to get the canvas material far enough off so I can rethread the end of the canvas material back through to ensure it seeds properly.

I've disassembled the inner frame so the two halves of the floor are no longer connected, but i still can't remove the fabric from the base. What am I missing here?!

Pics below for reference...

 

I folded it in half and stood it on its side. Luckily I was able to pull it back far enough to fix it without removing it entirely. Hopefully it doesn't happen again. Thanks