Multi strike lock needed

I need a three striker lock. Mortise multi lock replacement is not my area of expertise but based on these pics I can tell I need three of those locks to replace the broken one I have. How do I find that? The handle is in place and the the striker pad (? Keeper?) is still there on the solid glass door and the slider door needs this lock. How do I find it? I've taken it apart twice and it won't restrike the keeper and lock and engage. Ugh...