These Blog posts are about repairing an internal door latch where the latch now fails to fully return back into the door rebate or locking mechanism when you turn the door handle. the failure of the latch to fully retract inwards towards the door will leave part of the latch protruding out beyond the door edge. This protrusion can cause the door to lock in the closed position, thereby trapping the user on the other side.
In all instances the commentary in this and other parts does not supersede professional advice or the skill of a trades person. All tools should be kept out of reach of small children. You should wear safety glasses when working in close proximity of a screwdriver and when working with objects that include springs that could force an item to dislodge and spring towards the user. It is best to keep small children well away and supervised by another adult during the repair process in case a small child inadvertently closes the door and locks themselves on the other side. I am unable to accept any responsibility for the advice obtained in these Blog Posts as you are free to accept or reject the advice as you see fit.
Principles of operation of a door latch: the latch mechanism contains a square hole through which a metal bolt or bar slides through and engages into the hollow internal recess of the pair of door handles which are secured one on either side of the door. For the purposes of these posts I shall refer to the central 'bolt or bar', as simply the 'bar'. As the user moves the door handle, the metal bar also turns inside a square hole in the locking mechanism. This turning action of the handles and the metal bar, simply retracts the latch back into the door.
Photo 1: showing the latch, thumb lock, and metal bar visible when the door handle is removed
