Truth hardware

Is the thumb lever offset toward the bottom of the handle set? If so, I believe either our 82-087 or non-keyed 82-090 could work for you. Note that a broken thumb lever can be indicative of a mortise lock that is broken and needs to be replaced. To test, remove the handle set and try manually throwing the lock with a slotted screwdriver. If it doesn't budge, it's time for a new mortise lock. See our 82-265.