Broken or damaged cylinder: what to do?

The cylinder — or barrel — is the heart of your lock: it's the part that reads the key and drives the bolt. When it breaks, the symptoms are baffling: the key spins freely without engaging anything, or the opposite, it won't turn at all, or the whole cylinder shifts when you touch it. This guide helps you recognise a genuine cylinder failure, understand where it comes from, and make the right choices when it's time to replace it.

The symptoms of a broken cylinder

• The key spins freely — it makes a full turn with no resistance and the bolt doesn't move: the cam (the part that transmits the movement) is most likely broken or has come loose. This is the most common internal failure.
• The key goes in but won't turn at all, even with the door open — broken pins or a mechanism seized solid. If the resistance came on gradually, read our guide on a lock that won't turn first.
• The cylinder moves or pushes in when you handle it — the fixing screw has worked loose or the body of the cylinder is cracked.
• A piece of key is stuck inside — a special case with its own guide: broken key in the lock.
• Tool marks, a bent or drilled cylinder — this is no longer wear but an attempted break-in: secure the door first, replace afterwards.

Where does the failure come from?

Natural wear

A budget cylinder racks up tens of thousands of turns over ten years. The brass of the pins wears down, the springs tire, and one day the mechanism gives out — often without warning, unlike a gradual seizing-up. Certified-quality cylinders last considerably longer, which is precisely what you pay for.

One turn too many

The vast majority of the "sudden" failures we come across have a simple cause: someone forced it. A slightly bent key, a cylinder that was already catching, an energetic flick of the wrist on a rushed morning — and the cam gives way. If your lock is showing signs of fatigue, that's the moment to have it checked, not to crank harder.

An attempted break-in

Cylinder snapping (breaking the cylinder with a crowbar) is a common break-in technique on cylinders that stick out from the door. If you find your cylinder bent, torn out or drilled, don't disturb anything unnecessarily: take photos for the insurer, file a report, and have the door secured the same day.

What to do, in practical terms

If you're inside or the door is open: stop using that lock, even if it "still sort of works". A dying cylinder always picks the worst moment to give up the ghost — door shut, on a Sunday evening. Replacing a standard cylinder is a quick job you can plan for.

If you're locked out: this is a routine door opening for a professional. Depending on the state of the mechanism, the door is opened by lock picking or, if the cylinder really is dead, by targeted drilling — the cylinder is then replaced on the spot, without touching the lock or the door.

Choosing the right replacement cylinder

Replacing a broken cylinder with the same bargain-basement model just sets you up for the same cycle. Three questions to ask yourself:

• The size — a cylinder should never stick out more than 2–3 mm from the outside of the door: that's the first line of defence against snapping. The right move is to measure (or have someone measure) both sides from the central screw.
• The security level — anti-pick, anti-drill, anti-snap: these protections exist at every budget. Our guide on choosing a security lock compares the options.
• Control over copies — if you've just moved in or there are keys floating around, take the chance to switch to a security key with an ownership card: no one will be able to copy your key without the card.

Our lock replacement service keeps the main cylinder sizes stocked in our vans: in most cases the replacement is done in a single visit, the same day.