1. Check the yoke assembly # to verify it matches the # on the left side of the grip frame (also inside the side plate). If so, it's the original yoke.

2. The yoke screw is a bit short as posted by 29aholic. I did not extend deep enough into the groove ahead of the button. First remove the burrs on the side of the button/groove. Then do as he suggested, swap screws and shorten the other screw tip no more than it takes to eliminate resistance when closing the yoke.

3. If you get the screw short enough but you still feel resistance in opening and closing the yoke, relieve the side of the button the length of the worn groove showing in your photo, so the button doesn't bind on the side of the screw tip. Slight resistance is OK with lubrication, for a nice snug fit of the yoke.

This is too simple to fix, to waste time and money at a gunsmith.

__________________
Jim
S&WCA #819