The ejector sear has three critical surfaces. In the forend knuckle,the bottom of the "L" sets it as the cocking rod moves forward.The top then rises to catch the ejector hammer.The last surface is at the top of the knuckle and projects to the rear.As the barrels open,the last surface rides in its groove in the action knuckle.When the action groove ends,the sear trips.Check the two grooves on the action and check the two trip surfaces on the forend knuckle (they should be the same).