Expert advice on how to repair common problems with door knob locks and deadbolts, such as stuck or frozen door locks, latches that don’t latch, and keys broken off in locks.
Many door knob and lockset problems can be corrected before they become so serious that the lockset does not work at all. Often, a malfunctioning latch assembly or lock mechanism causes the problem. Here we look at repairs for locksets and knobs. If you have a key that won’t work in the lock, please see How to Repair Keyed Door Locks.
The lock mechanism may not work simply because the lock is dirty or dry and needs to be lubricated with graphite (do not use any type of oil because this will gum-up the works). An improperly functioning latch may be the result of a poorly fitting door.
For serious lock problems, it is usually best to call a locksmith or to replace the lock entirely. Most interior door knobs are relatively inexpensive to replace; it doesn’t really pay to have interior door knobs or locks professionally repaired unless they are special. You can buy door knobs online.
Exterior latches and locksets, on the other hand, can be very pricey. If you need a pro to fix problems with a high-quality door knob or lockset, removing the hardware and taking it to a locksmith is usually far less expensive than having the locksmith come to you.
When a door latch doesn’t click into position, it usually means the latch and the strike plate are out of alignment. Tighten the hinge screws and then try adjusting the strike plate by loosening its screws and shifting it slightly. Repairs range from making minor latch adjustments to repositioning the door.
If the latch does not catch, close the door slowly to watch how the latch bolt meets the strike plate. The bolt may be positioned above, below, or to one side of the strike plate. (Scars on the strike plate will show where it is misaligned.) It is also possible the door has shrunk and the latch no longer reaches the strike plate. Once you have figured out the problem, try one of the methods shown here.
When possible, it’s easiest to file the slot in the strike plate a little bit so that it will receive the latch. For less than a 1/8-inch misalignment of the latch bolt and strike plate, file the inside edges of the plate to enlarge the opening.
Shifting the strike plate’s position usually involves mortising the jamb, filling part of the old mortise, and so forth. You can also solve misalignment by replacing the strike plate with an adjustable door strike.
For more than a 1/8-inch misalignment, remove the strike plate and extend the mortise higher or lower as necessary. Replace the plate, fill the gap at the top or bottom with wood putty, and refinish.
If the latch does not reach the strike plate, shim out the plate, or add another strike plate on top of it (remove the screws and run them through both plates). If the latch still will not reach, shim out the door’s hinges. As a last resort, remove the door’s hinges and shim them to adjust the door’s position.
Door knobs may become loose over time. Methods of tightening them depend upon the type of lockset. You can tighten a simple interior mortise lockset like the one shown at left as follows:
1) Loosen the setscrew on the knob’s shank.
2) Hold the knob on the other side of the door, and turn the loose knob clockwise until it fits snugly. Then tighten the screw until you feel it resting against the flat side of the spindle. The knob should turn freely.
3) If this does not help, remove the knob and check the spindle; if the spindle is worn, it must be replaced. If the whole lockset is worn, it is best to replace it entirely. You can buy new door locksets online.
Exterior locks can freeze, interior locks get dirty, and small internal parts eventually wear out or break. Before you buy a replacement lock, try some quick remedies:
Put some graphite into the keyhole, either by squeezing it from a tube or dusting it onto a key, and then operate the lock a few times to work the graphite into the mechanism.
Lock de-icers contain alcohol and other lubricants that help to dissolve gummy, dirty deposits. The last resort is to disassemble the lock to see if something has jammed or is broken—you may be able to set it straight or replace the part without buying a whole new lock.
A cylinder turns when the setscrew(s) meant to hold it in place become loose or broken.
Mortise lockset: Remove the faceplate (if there is one) at the door’s edge and locate the one or two cylinder setscrews. They should be in line with the center of the cylinder. Tighten the setscrew(s) by turning clockwise—be sure they engage the slot that runs along the edge of the cylinder (the key slot should be perfectly vertical). Replace the faceplate.
Surface-mounted rim lock: Unscrew and remove the cover, called a “case.” Tighten the cylinder setscrews. Replace the case.
The chances are good that the bolt is having a hard time finding the throat in the strike plate. Be sure the strike plate is secure and in reasonable alignment with the bolt. You can file the edges of the strike plate a little, and even slightly round the edges of the deadbolt’s end. If this doesn’t work, you’ll probably have to remove the strike plate, fill the screw holes with glue and wood matchsticks, reposition it properly, and rescrew it in.
Using pliers, try to grip and pull the key straight out. If you can’t get a grip even with needle-nose pliers, cut off a coping saw blade and, with the teeth pointed outward, insert the blade into the keyway and try to hook and drag the key out. As a last resort, remove the cylinder. Insert a stiff wire into the cam slot at the back of the cylinder and push the key out. Or take the cylinder to a locksmith.
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