Lock assembly for an older sliding glass door

The locking mechanism doesn't work. the lock lever is loose and doesn't do anything.  I would like to replace this (the whole thing if necessary) with something more durable that works.  It's a nice door with the shades on the inside of door, so I would like to repair and keep it.  I haven't removed the parts yet, and I don't want to if I can get the right new parts.