Window awnings and slideout toppers are different animals when it come to increasing tension. I have done both. Mine are Carefree.
Window awning is pretty simple if there is a way to take the arm on each end loose without having to remove rivets. With the awing out, take the arm loose holding it so it doesn't get away with the speing tension. Then rotate the arm a revolution or two tighter, then resecure the arm. Mine were "floating" away from the coach in strong side winds, and two turns on each end stopped that. Since you are increasing the spring tension by hand, you should be able to easily tell if you reach the limit of the spring ...if you do, then back off a turn or so.
Slide topper awnings are a little more involved, but not difficult. The spring on Carefree toppers is on the left end (facing toward the side of the coach) only. The is a hole in the roller near the end that can be used to pin the spring, or the roller has slots that can be used with a screw driver and the end bracket. With the roller pinned, I retracted the slide an estimated revolution or two. Then, on a Carefree, the roller is released from the bracket by loosening the bolt through the center of the roller. With it loose, I manually turned the roller to take up the slack, the resecured the roller, and unpinned the roller to release the spring. With the roller secured and unpinned, I then extended the slide. CAUTION: If you increase tension too much, when you extend the slide it is strong enough to destroy the spring/fabric/anything else that won't give! ...a little at a time is better than a lot ...I did mine twice before I decided not to push it more.
Remember, you are dealing with fabric ...it WILL SAG some (especially when water is on it) and it WILL FLAP some in strong winds. You WILL destroy the fabric and/or something else before you "take up all the slack". (Look at how powerlines, and even steel cables holding powerlines, sag between poles ...it can only be made so tight before something has to give...)
Paul (KE5LXU) ...was fulltimin', now parttimin'
'03 Winnebago UA 40e / '05 Honda Odyssey toad