B. Dudly, Thanks for the reply.
Although this gun is marked "The Fulton" the sear set-up is not as shown in the schamatic, that I could find for this gun. They are set up as shown for the "Ranger" and are in the bottom of the action.
The sears look like someone has clumsily worked on them, to lighten the trigger pull (which is very heavy) and may be the reason the sears fail to catch.
Thanks again, Pete