Changing a cylinder lock

Standard cylinder locks are also called night latch locks or Yale locks. They are fitted on the front door, which should also have a 5-lever mortice lock.
Both are easy to remove and replace with screwdrivers. Remember, you don't need to buy the whole lock set, just the cylinder.
- Undo the screw on the lock body and remove it (keep the screws safe).
- Undo the two long mounting plate screws.
- Take out the old cylinder.
- Put the new cylinder into the hole from the outside and secure it to the mounting plate from the inside of the door with the old connecting screws.