Stiff lock or catching key: the 5 causes and their fixes

It started discreetly: one morning the key caught a little. Now every opening is a negotiation — and such negotiations end in a snapped key or a door that won't open. Behind a stiff lock hide five well-known causes, each with its fix.

Cause 1: a dirty, unlubricated cylinder

The most common and most neglected. The cure costs under €10: dry lubricant (graphite or PTFE) puffed into the keyway once a year. The deadly trap: cooking oil or greasy degrippant — instant relief, medium-term death, as the greasy film traps dust into an abrasive paste.

Cause 2: the key itself

Keys wear; badly cut copies are born worn. The decisive test: try the original key from the drawer. If it turns perfectly while your daily copy catches, have a new copy cut from the original — never from the worn copy. And retire any key with a hairline crack at the neck: extraction of a snapped key costs €90–150, a fresh cut a few euros.

Cause 3: the door has moved — the most common false culprit

Weekly scenario: the customer suspects the lock; the lock is fine — the door has settled or swollen, and the bolt drags on its strike. Clues: the symptom varies with the weather, you lift or pull the door to lock comfortably, shiny drag marks on the strike. The fix is an adjustment (€90–250), not a new lock — on security doors it is even standard maintenance.

Cause 4: a tired mechanism

Sagging springs, a loose follower, desynchronised multipoint rods: many of these repair by the part (€90–250) when the lock is not obsolete. Our rule: when repair passes one third of a new lock fitted, we show both options side by side.

Cause 5: the unnoticed break-in attempt

A cylinder suddenly stiff overnight may have been attacked — brutal picking, a forced screwdriver, glue. Clues: fresh scratches around the keyway, fine metal shavings. Don't wait: a wounded lock can fail within days, and if a second visit is planned, better it finds a new, better-armed cylinder.

The method in five steps

1. Test the original key. 2. Check weather-dependence and drag marks. 3. Lubricate dry. 4. Sudden symptom + marks → professional inspection. 5. None of the above → mechanism diagnosis. And the rule of rules: never insist on a key that resists abnormally — that is exactly how Sunday-night extractions are born. Prevention is one dry-lube shot a year and a seasonal glance at the door's play: ten minutes that spare you our night rates.

FAQ

Stiff only in winter? Seasonal door swelling — a proper adjustment beats planing, which leaves the door loose in summer.

Can a stiff lock heal itself? Never durably. Acting at the "it catches" stage costs three to five times less than at the "it's jammed" stage.