I had a similar issue with the Globetrotter. The rail on the trailer was crimped every 6 or 8 inches.
I tried tapping, tugging, swearing and attemting to expand the rail without any success. There was too much friction from the disintegrating fabric and dirt to even move it an inch.
I ended up cutting through the plastic spline at the center of the rail with a hooked ex-acto knife blade. I thought that by taking it out in sections might be easier.
To my surprise the plastic spline easily slipped right out of the rolled fabric seam. Now without any tension on the awning it slid out of the rail in one piece.
Since it appears you're going to be re-doing the seam this might be an option for you.
AirForums # 2806
WBCCI / VAC # 6411
Not All Who Wander Are Lost.
Avid supporter of trailing edge technology.