Troubleshooting & Repair of Locks Flashcards

A padlock shackle will not release after the correct key is fully turned. Which condition best explains this symptom?

Answer: Shackle under lateral load or tension

Padlock shackles under lateral tension or load bind the locking dog and prevent release even after the plug rotates correctly; tension must be relieved before the shackle will open.

Which symptom most clearly indicates that a lock's plug has excessive side play (slop) within the shell?

Answer: Plug wobbles during key insertion with no binding on pins

Excessive side play causes the plug to wobble without properly engaging the pins, indicating wear between the plug and shell.

A technician is troubleshooting a Schlage B-series deadbolt where the inside thumbturn works but the key cylinder does not retract the bolt. The most likely fault is:

Answer: Stripped cam on the cylinder

If the thumbturn operates correctly but the key side does not, the cylinder's cam that drives the bolt mechanism is the component to suspect.

After re-assembling a cylinder, the plug does not rotate freely with the correct key but did before disassembly. The technician should first check:

Answer: Whether driver pins were accidentally swapped between chambers

Swapping driver pins of different lengths between chambers during disassembly can cause false shear lines or binding, preventing smooth rotation.

A lever handle lock returns to the horizontal position slowly or not at all after being depressed. The technician should inspect the:

Answer: Return spring or spring cage

The lever return spring or spring cage is responsible for returning the lever to its resting position; failure of this component causes the slow or no-return symptom.

When inspecting a high-security lock cylinder for wear, which measurement tool is used to verify pin chamber depth tolerance?

Answer: Depth gauge or micrometer

A depth gauge or micrometer measures pin chamber tolerances precisely to identify wear beyond manufacturer specifications in high-security cylinders.

A customer complains that their electronic keypad lock's motor runs but the bolt does not move. The mechanical fault is most likely in the:

Answer: Coupling clutch or drive gear between the motor and bolt

If the motor runs but the bolt is stationary, the mechanical coupling or drive gear between the motor output and the bolt mechanism has failed or slipped.