Help with retensioning Carefree topper awning

A friend was helping me replace the fabric on my Carefree of Colorado slide out topper. I thought he understood about pinning the spring before we removed the roller. Well, he didn't insert the cotter pin and I lost all tension on the spring.

I've got the instructions about increasing tension but not from scratch. Just can't find the specific instructions on the Internet. Can someone here help?