Locks Wear Out — Here's How to Tell
Door locks are mechanical devices. They have springs, pins, and moving parts that wear down over time. A lock that's starting to fail won't always break completely — it gives warning signs first. Catching these early can mean a $50 repair instead of a $250 replacement after a complete failure.
Here are the signs to watch for.
1. The Key Is Hard to Turn
If you have to jiggle, force, or wrestle your key to get the lock to turn, something is wrong. Possible causes:
- Worn pins — Internal pins are wearing down, causing misalignment
- Rust or corrosion — Moisture has entered the cylinder
- A worn key — Your key is wearing down, which damages the lock pins over time
- Misaligned door — The door has shifted, so the bolt doesn't line up with the strike plate
What to do: Try a spare key first — if the spare turns smoothly, your main key is worn and you need a new one cut from the original code. If the spare is also stiff, the lock needs cleaning or repair. Don't force it — a broken key inside the lock is a bigger problem.
2. The Key Won't Go All the Way In
If the key stops partway into the lock, something is blocking the keyway. Common causes:
- Broken pin or debris — An internal pin has broken or debris has entered
- A broken key fragment — A piece of a previous key is stuck inside
- Dirt or corrosion buildup — Especially on exterior locks exposed to weather
What to do: Don't force the key. If it's a broken key fragment, a locksmith can extract it. If it's debris or corrosion, the lock may need cleaning or replacement.
3. The Bolt Doesn't Extend or Retract Fully
If you turn the key and the deadbolt doesn't fully extend into the strike plate, or it gets stuck partway, the lock isn't securing your door. This is a serious security issue — a partially extended bolt can be pried open.
Possible causes: worn internal mechanism, misaligned strike plate, or the door frame has shifted.
What to do: This needs professional attention. A locksmith can determine if it's a lock problem or an alignment problem. If the lock is old, replacement is often the best option.
4. Visible Rust or Corrosion
Locks on exterior doors are exposed to rain, humidity, and temperature changes. Over time, corrosion eats away at the internal components. If you see rust on the keyway, the bolt, or the lock body, the internal damage is likely worse.
What to do: A lightly corroded exterior can be cleaned. But if the keyway shows rust, the internal pins are probably corroded too. Replacement is the safe choice, especially for your main entry door.
5. The Lock Turns but Doesn't Lock
If you turn the key and hear/feel it engage, but the door still opens, the internal mechanism is broken — the tailpiece or cam that drives the bolt has failed. This is a complete lock failure.
What to do: Replace immediately. The lock provides no security in this state.
6. The Lock Is Loose or Wobbly
If the lock cylinder or the entire lockset moves when you insert the key, the mounting screws are loose or the lock body is damaged. A loose lock can be forced open more easily.
What to do: Tighten the mounting screws. If the lock is still loose, the door or the lock body may be damaged and need replacement.
7. You've Been Using the Same Lock for 10+ Years
Even with no visible issues, a lock that's been in daily use for 10+ years has significant wear. Springs weaken, pins wear down, and the mechanism becomes less reliable. More importantly, lock technology has improved — a 15-year-old lock may not meet current security standards.
What to do: Consider preventive replacement, especially on your main entry door. Upgrading to a Grade 1 deadbolt is a security improvement, not just a maintenance task.
8. After a Break-In or Attempted Break-In
If someone tried to force your door, the lock may be damaged even if it still works. Internal components can be bent or weakened. A damaged lock may fail when you need it most.
What to do: Have the lock inspected by a locksmith. In most cases, replacement is recommended after a forced entry attempt — the damage isn't always visible.
Repair vs Replacement: A Guide
| Problem | Repair or Replace? | Typical Cost |
|---|---|---|
| Worn key (spare works fine) | New key cut | $5 – $20 |
| Stiff but functional | Clean and lubricate | $20 – $50 (DIY: graphite spray) |
| Misaligned strike plate | Realign (repair) | $50 – $100 |
| Broken key in lock | Extract + repair | $50 – $125 |
| Rust/corrosion | Replace | $75 – $250 |
| Bolt won't extend | Replace | $75 – $250 |
| Lock turns but doesn't lock | Replace immediately | $75 – $250 |
| After break-in attempt | Replace | $75 – $250+ |
FAQ
How long do door locks last?
Quality deadbolts last 10-15 years with proper maintenance. Cheaper locks may last 5-7 years. Exterior locks wear faster due to weather exposure. Replace any lock that's 10+ years old on a main entry door, even if it still works.
Should I repair or replace a stiff lock?
Try cleaning and lubricating first (graphite spray, not WD-40). If that doesn't help, try a spare key. If the spare is also stiff, the lock needs professional attention. For locks under 5 years old, repair may be cost-effective. For older locks, replacement is usually better.
Can I use WD-40 on a stiff lock?
No. WD-40 is a solvent, not a lubricant. It will temporarily loosen the lock but then attract dust and grime, making the problem worse. Use graphite powder or a silicone-based lock lubricant instead.
How much does it cost to replace a door lock?
Lock replacement costs $75-$250+ per lock, including hardware and labor. The price depends on the lock grade (Grade 3 is cheapest, Grade 1 is most expensive) and whether it's a standard deadbolt or a high-security lock.
Need lock repair & replacement service right now? Call (855) 373-1159 and our 24/7 dispatch center will connect you with a licensed professional near you.