I have three door security doors, one recently wouldn't open. I had a locksmith come out and take the handle off. He said that the mechanism that locks broke and would need to be replaced. He has had the part for a couple of weeks and has stated that he is looking for the part.
While searching for the part online this morning, I came across your website. The Mortise Lockset looks very similar to my doorhandle. I am including pictures of my door handle so you can see what it looks like, and hopefully, tell me if you have something that would work in its place or if you might have a part. I would just purchase a new lock from the guy who installed; however, he is not longer in business.