IF it's a torsion spring assembly - a coiled spring with a 1" hollow steel shaft running right thru the middle of the spring similar to what's found on a garage door, then I suggest calling a local overhead/garage door company to replace the spring. These springs are sized based upon wire diameter, the overall coil inside diameter and length. The new spring needs wound and there are very specific winding bars needed in the cone end in order to do so - these springs contain enough energy when wound to remove fingers from hands and hands from arms.
I do not suggest this project as a DIY project.
94-Newmar Kountry Star 40-KSDP
Spartan/Cummins 8.3C-300HP/Allison 3060 WTEC-II/25yr RV Tech RVIA Certified/Onan-Cummins Certified