Since you do not tell me who manufactured your Slideout Topper Awnings it will be very hard for me to tell you how to adjust the tension on them. Depending on the make and model there is a different method to adjust the tension.
There are two main manufacturers of Slide Topper Awnings Dometic A&E and Carefree Of Colorado. If you visit the links I just mentioned you will find that depending on the model that you can download a manual that will walk you through adjusting the tension of your Slideout Topper Awnings.
If it ends up that you need new slide toppers you should watch the video below showing how easy it is for a do-it-yourselfer RVer to install them.
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