A Latch That Stops Catching
The Cheapest Diagnostic You Own
A latch is a fixed point on one leaf meeting a fixed point on a post. It has almost no moving parts and it does not wear quickly. So when it stops meeting, the overwhelmingly likely explanation is that one of those two fixed points has moved. That makes the latch a precise indicator of movement elsewhere, and a free one.
Which Way Is It Missing
The direction tells you the cause. Missing low means the leaf has dropped, which is a hinge or a hinge post problem. Missing to one side horizontally means a post has rotated or the frame has racked. Catching but needing a shove means the gate is arriving short, which is either a stop that has moved or an operator limit that has drifted. Each of those is a different job.
Why Moving the Keeper Is a Trap
Slotting the keeper and shifting it to meet the gate where it now arrives works immediately and is nearly free, which is why it is so often done. The problem is that whatever moved the gate is still moving it. Within a year the keeper needs moving again, and by the third adjustment the underlying fault has usually progressed from an adjustment into a repair. Each adjustment also removes the only signal that would have told anyone.
Measure Before Adjusting
Write down the gap at the top and the bottom of the closing edge and the height of the leaf above the ground at the free end. Those three numbers take a minute and turn the next visit from an argument into arithmetic. A gate that has dropped a quarter of an inch since last year is on a trajectory; a gate that has dropped an inch has a problem now.
Electric Strikes and Magnetic Locks
An automated gate often carries an electric strike or a magnetic lock rather than a mechanical latch, and these are far less forgiving of misalignment. A magnetic lock needs its armature plate flat against the magnet to hold anywhere near its rated force, so a leaf that has sagged slightly can leave a lock that reports as engaged while holding a fraction of what it should. That failure is silent and worth testing for rather than assuming.
Fixing the Cause
Once the movement is corrected, the latch usually needs no work at all: it lines up again where it was originally fitted. That is the confirmation that the diagnosis was right. A gate that still will not latch after the hinges and post are sorted has a racked frame, and that is a fabrication job rather than an adjustment.