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. An improperly functioning latch may be the result of a poorly fitting door. 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).
Fixing a door knob is a job just about anybody can do.
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 these 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 come to you.
Door Latch Is Misaligned
If a door latch does not operate smoothly, the latch bolt on the door may not be lined up properly with the strike plate on the doorjamb. 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.
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.
If the latch does not reach the strike plate, shim out the plate, or add another strike plate. If the latch still will not reach, shim out the door’s hinges. Replace the door with a wider one as a last resort.
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.
Doorknob Is Loose
Doorknobs 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.