To all those who offered up their lock problem solving skills under the previous topic "Inconsistently half cocked situation": Thanks.... and to close the loop.
The solution was a longer fly.
After comparing the old fly and new fly in operation, these quotes from member EC121 were right on:
“If the fly nose is level with the tumbler it is too short.” That's the way it was.
“The point of the fly should extend a bit past the edge of the half cock notch for the sear nose to push it out of the way for half cocking.” That's the way it is now.
Works fine.