If the OEM parts are no longer available and NOS is depleted then you have three basic choices to address your broken spring assembly issue:
1. Find a "Donor" awning to cannibalize parts from. This is easy with commonly used brands, and harder with less popular brands. Also, if yours are broken, then it is likely that donor unit springs may be broken, or worn out.
2. If you're very handy, adapt currently available spring assemblies to fit your awning. I've done this with slightly used AE spring assemblies in an old Carefree awning on our 76. It involved some machining in my case, but the end result worked well. You are better off buying the spring assembly rather than trying to find an individual spring, and you'll need left hand and right hand assemblies.
A word of caution inserted here. Torsion Springs can be very dangerous, as such I would discourage anyone from working with awning springs unless you are experienced (properly trained) or have a good mentor.
3. Buy a new awning.
Take some photos and measurements then post them here and maybe we can help you further.
"One of the best lessons I've learned is that you don't worry about criticism from people you wouldn't seek advice from."
William C. Swinney