I would "score" the trigger plate where the tip of the fullcock notch tip rest when at full ****. (See the arrow in your pic below). Then as you pull the hammer back from the resting position, see if the halfcock notch tip "covers up" that score. If so, some filing of the halfcock notch tip would be in order.
This may take a few "file the tip", reassemble, try, file the tip, etc, etc.
This may take a few "file the tip", reassemble, try, file the tip, etc, etc.
