Remove the screws that hold the knob in place so you can remove one part of the lock cylinder from the door.
2. Locate the set screw holding the cylinder in the door.
The most common spot for this is through a small hole in the edge of the door, next to the door handle. There is a tiny screw inside this hole that engages a slot on the cylinder.
3. Remove the lock cylinder.
Use a small flathead screwdriver or Allen wrench to remove this set screw. This releases the cylinder, and you should be able to pull it straight out of the door.
4. Inspect the lock cylinder.
Look for any visible damage, such as broken springs or misaligned pins. If you see anything that looks broken, the cylinder will need to be replaced.
5. Clean the lock cylinder.
Gently wipe the cylinder with a clean cloth to remove any dust or debris. If the cylinder is very dirty, you can use a mild detergent and water. Be sure to dry the cylinder thoroughly before reinstalling it.
6. Reinstall the lock cylinder.
Insert the cylinder into the door and tighten the set screw. Replace the door knob and screws, and test the lock to ensure it works properly.
