Lock Issues

Composite Door Key Won't Turn

Key won't turn in your composite door? Don't force it - here's how to diagnose the cylinder, gearbox and alignment in the right order.

Written by Cornwall Composite DoorsReviewed by Cornwall Composite Doors installersLast updated July 20262 minute read

Overview

A key that won't turn falls into three buckets: cylinder problem, gearbox problem, or you haven't lifted the handle. Force is the enemy - a snapped key inside the barrel turns a £15 job into a £150 one.

Symptoms

  • Key goes in fully but won't rotate.
  • Key rotates partway then stops solid.
  • Key rotates but nothing happens.
  • You have to jiggle the key to make it work.

Common causes

  • Handle wasn't lifted first - multi-point locks need this every time.
  • Cylinder pins are worn or dirty.
  • Gearbox has failed and the cam won't drive.
  • Wrong key, or key has worn out of tolerance.
  • Cylinder has been partially snapped by an intruder attempt.

When to call a professional

  • Key has partially snapped inside.
  • Cylinder shows any sign of tampering.
  • Nothing has worked and you're locked out.

Prevention

  • Lubricate the cylinder twice a year with a graphite or PTFE lock spray - never WD-40 or oil.
  • Grease the hooks and rollers on the door edge every 6 months.
  • Always lift the handle to engage the multi-point locks before turning the key - this takes load off the gearbox.
  • Never force a stiff key - book a service call before the mechanism snaps.

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