You don't say what brand you have, but they're probably CareFree of Colorado or Dometic. Here's CareFree's web page http://www.carefreeofcolorado.com/ca...&categoryid=47
click on Technical PDF files mid page. Page 14 references spring info. http://www.carefreeofcolorado.com/do...e%20Manual.pdf
Dometic will have one similar. Be sure your end brackets aren't skewed and binding up the roller tube before you go to the trouble of winding up the spring. As stated in the literature, cotter key to hold spring in place and a second set of hands will be very helpful.