Re: tension on my slide topper...
IF you are mechanically inclined, the spring can be tightened. You have to drill out the pop rivets that hold the end caps on. Be careful, there is spring tension!!! The springs is these things are small and you might get ONE turn to tighten it up. That will do a LOT. You will really have to be holding it when you release the last rivet. I cannot impress that strong enough. My finger nailis still healing from the last awning spring that got away from me.
Becky is right, a basketball in the center might be a much easier fix!!