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Troubleshooting & Repair of Locks Flashcards

7 cards from real CPL practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Troubleshooting & Repair of Locks flashcards as text

  1. A mortise lock cylinder spins freely when the key is turned but does not retract the bolt. What is the most likely cause?

    Answer: Broken cam or tailpiece

    A freely spinning cylinder with no bolt movement indicates the cam or tailpiece connecting the cylinder to the bolt mechanism is broken or detached.

  2. Which lubricant is generally recommended for pin tumbler lock cylinders to avoid attracting dirt and debris?

    Answer: Graphite powder

    Graphite powder is the preferred dry lubricant for pin tumbler cylinders because it does not attract dirt or gum up the internal components.

  3. A wafer tumbler lock is difficult to turn even after the correct key is inserted. Which condition is the most probable cause?

    Answer: Worn or deformed wafers binding in the housing

    Worn or bent wafers that drag against the housing create binding, making the lock hard to turn even with the correct key.

  4. When disassembling a pin tumbler cylinder for repair, a follower tool is used primarily to:

    Answer: Keep the driver pins and springs from falling out

    A follower maintains pressure on the driver pins and springs so they stay seated in the shell when the plug is removed.

  5. A deadbolt throws only halfway before stopping. After ruling out hinge and door alignment issues, what internal component should be inspected next?

    Answer: A broken or weak bolt spring

    A weak or broken bolt spring can prevent the deadbolt from completing its full throw, causing it to stop partway.

  6. During rekeying, a locksmith discovers one pin chamber has a driver pin that is too short. The most likely symptom of this defect is:

    Answer: The lock opens without a key (false set)

    An undersized driver pin may allow the plug to rotate without all pins reaching the shear line, creating a false set or unintended opening.

  7. A customer reports their knob lock's latch does not retract fully when the knob is turned. The most common mechanical cause is:

    Answer: A broken or seized latch spring

    A broken or seized latch spring prevents the latch bolt from fully retracting when the knob is turned, even if the mechanism is otherwise functional.