The drivers door handle on my 65 544 drooped a lot. The passenger side, witch is used a lot less is fine.
I took the door latch out of the door and checked it out. The only problem with it, other than needing lubrication, was the square hole that the square rod attached to the door handle passes through. The hole was worn especially near the corners. The rod on the handle was in good condition but much easier to make it bigger than to make the square hole smaller.
I put a small weld bead (MIG welder) on two sides of the last 3/4 inch on the rod. Then using a bench grinder and then a Dremel tool for fine tuning, I fit the rod to the worn hole. The door handle is now nice and straight.