Identifying a mortise lock

I have a mortise lock that is defective. I think a spring is broken. The lock hook tends to get stuck inside rather than "reaching out" to grab the catch on the door frame. I think I need a 82-218 but I'm not 100% sure. I don't know who made the door. The inside handle looks like a 82-035 but the outside handle is different. Of course, this is all from appearances. I was hoping for part numbers.

Please help!

Thanks,
Alan