Troubleshooting & Repair of Locks Flashcards

A locksmith is repairing a rim lock where the deadbolt sometimes retracts with the key and sometimes does not. This intermittent behavior most likely points to:

Answer: Worn or cracked bolt spring causing inconsistent tension

An intermittent failure with the correct key usually indicates a spring that is partially broken, producing inconsistent tension and unpredictable operation.

When troubleshooting a cylindrical lockset where the latch bolt has broken off flush with the face of the door, which method allows the door to be opened without damaging the frame?

Answer: Removing the lock body via the rose screws and manually retracting the mechanism

Removing the lock body by backing out the rose screws exposes the mechanism so the broken latch can be retracted manually, preserving the door frame.

A Grade 1 cylindrical lockset fails the ANSI/BHMA cycle test during repeated use. Which internal part is statistically the most common failure point in field service?

Answer: The latch spring or latch mechanism

The latch spring and latch mechanism are subjected to the highest mechanical stress per operation cycle and are the most common wear failure points in cylindrical locksets.

Which procedure should be performed before attempting to rekey a cylinder that exhibits stiff key operation?

Answer: Clean and lubricate the cylinder, then test for smooth operation

Cleaning and lubricating removes debris and dried lubricant that cause stiffness; testing afterward confirms whether rekeying or part replacement is still needed.

A lock cylinder that has been drilled during an emergency entry should be replaced rather than repaired primarily because:

Answer: Drilling compromises the structural integrity of the plug and shell, eliminating security

Drilling distorts pin chambers and the plug-to-shell tolerances, permanently compromising the security and functionality of the cylinder.

A sliding door lock's latch bolt does not fully engage the strike in the closed position. After confirming the door slides fully closed, the technician should:

Answer: Adjust the strike plate position or depth to align with the bolt trajectory

Strike plate misalignment is the most common cause of incomplete latch engagement; repositioning or deepening the strike corrects the bolt's path into the keeper.

During troubleshooting, a locksmith discovers a broken key fragment lodged in a pin tumbler cylinder. The proper extraction technique uses:

Answer: Broken key extractors inserted alongside the fragment to engage the serrations

Broken key extractors have hooked or serrated tips designed to grip the key fragment's cuts and pull it free without damaging the cylinder's internal components.