Just came accross this topic, and have an easy solution. My 62 544 still had the original {broken} spring in place.It is a "Hairpin" type similar to a large safety pin.The center coil goe over the pivot pin at the left bottom of the door, one end has a hook that locates over the back edge of the bracket leg that is upright when the door is closed,and the other end is bent at 90 degrees to lie in the groove along the door frame bottom, pointing to the passenger door.
My solution was to buy a packet of two "Cotter Pin - Safety Pin" 058X 1- 3/4
#058, look in misc hardware drawers at Home Depot - 90 Cents! You'll only need
to straighten the plain leg so the two legs are almost at 180 deg. to each
other, then put in the 90 deg. bend about 3/8" from the center coil. {It's a lot simpler than it sounds}