There are a number of U-Tube videos about replacing slide out topper fabric. The first part of each shows how to "pin" the roller so the spring is locked.
There is a hole at the end of the roller that you can insert a pin into (I used an old fashioned ice pick) and all the way through the roller tube. This is usually at the right end of the awning, but there may be a hole at each end.
Two people are absolutely necessary. You cannot reach both ends at once.
-Run the slide all the way out.
-Pin the roller.
-run the slide in, leaving it about 8" open.
-Unscrew the brackets holding the ends of the awning to the face of the slide.
-Lay the roller and awning up on the roof of the trailer.
Replace the seals.
Reinstallation of the awning/topper is the reverse of removal.
Put plenty of non-sag caulk under the brackets and in the screw holes.
Be very careful when pulling the pin(s).
Not hard; just fussy work.
