replacement internal lock

The only identifier on patio door lock is Canadian Patent No. 919213 1973. Spring came out of internal mechanism; lock in open position falls closed/locked. Lock assembly (including screw hole ears) is 3.5" high, 0.875" wide, and 0.373" deep. Plastic shell (same patent no.) for lock assembly is 7.3125" high, 1.0" wide, and 0.875" deep. Shell is reusable. Does Swisco have a replacement lock assembly?

The lever may be too short. Your original mortise stuck out a little beyond the housing. Look at how deep the lever goes and think about whether you need a new lever before purchasing.