New Window Spring Needed

This looks like a Series 795 Channel Balance. Unfortunately due to the damage I can't totally make out what you have here. Can you produce an undamaged version and show me that bottom T-Lock Shoe? I want to see if it more closely resembles our 15-195 or 15-195B. As far as how the balance attaches to the window track, does it use a screw clip or a hook like our 15-198? If it's the hook, can you show me the hole in the window track it connects to? What is the length of the metal channel, not including the shoe? Is it 21" long? Finally, we'll need the exact weight of the window sash to pick a new stamp option, since that code 20-9 is from a rating system no longer in use. Many thanks. 

This is a huge help, thank you. I think my earlier assessment was accurate, based on these new photos. I believe our Series 795 channel balance will work perfectly fine for you as-is. Look it over and let me know if you agree, or if you had any questions.