Vintage Mortise lock with broken deadbolt spring , need help

[Marie]

This is one of the 14 similar mortise locksets in my 1928 house. The face plates are labeled Y52, Y56. Y57 or Y58. All of them have the same broken and or missing hairpin spring, shown below the lockset, which, I assume, is to facilitate the operation of the key and deadbolt mechanism. All of the know latches work fine.I could fabricate a new spring from memory wire or spring wire, but I don't know where the spring is supposed to brace against. Does it wrap around the screw post? If so, what are its ends anchored against. I have carefully opened each lock, and NONE of them have an intact hairpin spring.

Any help out there? thanks.