If your deadbolt only locks while you push, pull or lift the door, the lock itself may not be the problem. The bolt travels partway across, meets something solid and stops. You lean on the door, or pull it toward you, and it slides home. It is easy to read that as a failing lock. Often the deadbolt still works, but the door, hinges or strike plate are no longer lining up properly.

The one thing worth doing straight away is to stop forcing it. Every time you force the thumb turn while the bolt is caught on the strike plate, you put extra pressure on the parts inside the deadbolt. A loose hinge or small alignment problem can eventually damage the deadbolt if you continue forcing the lock.

Test the deadbolt with the door standing open

Before adjusting the hinges or buying a new lock, open the door and extend the deadbolt with nothing in front of it. It takes a few seconds, and it separates a lock problem from an alignment problem, which are two completely different repairs. What the bolt does with nothing in front of it tells you which one you have:

Where the bolt goes when you lock the door

A deadbolt on a house door throws about an inch. It passes through the strike plate screwed to the jamb and into a box or a drilled pocket in the frame behind it. The pocket needs enough depth and clearance for the bolt to extend fully without rubbing. The strength comes from the bolt extending fully through a secure strike plate and into the pocket behind it.

Even so, the opening is not much wider than the bolt, which is why small movements cause so much trouble. An eighth of an inch anywhere in the door, the hinges or the frame is enough to bring the bolt down onto the lip of the plate instead of through the opening. Pushing or pulling the door flexes everything back into line for a moment, which is long enough for the bolt to find the hole. That pressure only moves the door into alignment for a moment. The underlying problem is still there.

It is also why the latch below the deadbolt usually carries on working perfectly. A latch has a short throw and a beveled face that lets it ride over the plate and drop in, and its hole is far more forgiving. The deadbolt has no tolerance to spare, so it fails first, and it is the part that tells you something has shifted.

Quick things to rule out before you blame the door

Sometimes the door has not moved at all. Before adjusting the hinges or frame, check for these smaller problems that can keep the bolt from entering the strike pocket:

When the door has dropped on its hinges

If the movement that makes it lock is upward, so that you find yourself lifting the handle or the edge of the door before the bolt will go, the hinges are the place to start. The top hinge carries most of the weight of the slab, and the screws supplied with door hardware are often short enough to bite into the jamb only rather than the framing behind it. Several signs point at this one:

The repair is often simple. Go over all three hinges with a screwdriver, find the screws that spin, and replace at least one screw in the top hinge with a three inch screw that reaches through the jamb into the stud behind it. Plenty of doors lift straight back into line as that screw pulls tight, so try the bolt again before doing anything else.

When the door is not closing all the way

If the movement is inward, and you have to push the door toward the frame before the bolt will go, the door is not closing fully against the stop, so the bolt stops at the face of the strike plate instead of entering the opening. A few things hold a door out like this:

Doors that only do this at certain times of year

Wood takes up moisture and gives it back again, and frames move with the ground underneath them. Across much of Texas the clay soils swell through wet spells and shrink through dry ones, and a house sitting on them moves by small amounts as they do.

The pattern is what identifies it. The door locks perfectly for months, catches for a few weeks, then settles down on its own without anyone touching it. This does not necessarily mean anything has broken. If the alignment changes with the seasons, moving the strike plate during the worst spell may only solve the problem temporarily. These doors are worth having looked at during a quiet spell, when the alignment can be set properly rather than forced into working.

How to find out exactly where the bolt is landing

You can learn a great deal from where the bolt touches the strike plate. Before changing any hardware, use these four checks to narrow down whether the problem is the lock, the hinges or the door alignment:

What a partly seated deadbolt is actually holding

A deadbolt is strongest when the bolt extends fully through a secure strike plate and into the pocket behind it. Long screws that reach the framing behind the jamb help the strike resist force.

A bolt that has only caught the edge of the hole, or gone in halfway and stopped, can feel locked from the inside while holding a fraction of what it should. It is worth pushing the door with your hand before you leave the house or go to bed, rather than trusting how the thumb turn felt on the way past.

Do not start by filing the strike opening larger or moving the plate without first finding out why the bolt is missing. A small strike adjustment can be a proper repair when the door is stable, but the bolt must still extend fully and the strike must remain securely anchored. If the hinges, door or frame are still moving, enlarging the opening will only hide the cause.

When this stops being a job for a screwdriver

Some doors only need a loose hinge tightened or a longer hinge screw installed. Others have a frame or a slab that needs proper work, and buying new hardware for those is money spent on the wrong part of the door. Any of the following is a point to stop and have it looked at:

If the deadbolt works properly but the handle turns without opening the door, that is the latch side of the same door, and here is what to check when the doorknob turns but the door will not open.

Get your door closing and locking properly again