01
Start with the key
A worn, bent or freshly cut copy key is the most common cause. Try a spare if you have one. If the spare works smoothly, the original key is the problem, not the lock.
02
Check the door, not just the lock
Pull or push the door firmly towards the frame and try the key again. If it suddenly turns, the bolt is binding against the strike plate — an alignment issue, often seasonal as timber swells.
03
Dirt and dryness
Grit inside the cylinder stops pins lifting cleanly. A dry graphite or PTFE lock lubricant can help. Avoid oil-based household sprays — they attract dust and can make things worse over time.
04
Worn or broken pins
If the key goes in but feels "mushy", or works only at a certain angle, internal pins may be worn. This is not a DIY fix; the cylinder usually needs servicing or replacing.
05
What not to do
Never force the key with pliers — a snapped key inside the cylinder turns a stiff lock into a lockout. If gentle checks fail, stop and get advice.