Locate the small tumbler switch inside the mortise case (shown in the top-right circle). Use a screwdriver or your finger to push it upward.
Step 2: While the tumbler is pushed up, press the latch bolt into the case, rotate it 180°, and then let it spring back out.
2. Set the Directional Screw
This is the most critical part for ensuring the lock "knows" which side is inside versus outside.
The Rule: The directional screw must be installed on the interior side of the mortise.
The Placement: If you are standing inside your house looking at the door, the screw should be on the side of the mortise facing you