How to Reset a Master Combo Lock

Written by elizabeth falwell
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How to Reset a Master Combo Lock
(Medioimages/Photodisc/Photodisc/Getty Images)

Master Lock is a company that manufacturers dozens of styles of locks, including locks for luggage and backpacks, lockers and bikes. The company's "Set Your Own Combination" locks allow users to reset their combinations.

Skill level:
Moderately Easy

Things you need

  • Current combination
  • Reset tool (if applicable)
  • New combination

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    Models 175-178

  1. 1

    Open your lock using the original combination (supplied by the manufacturer) or a combination you've previously chosen.

  2. 2

    Locate the "reset tool" included in your lock's original packaging; this tool looks like a small key. Insert the key into the side of the Master Lock.

  3. 3

    Rotate the key a quarter-turn to the left or right. This initiates the reset process.

  4. 4

    Move the numerical wheels to the desired combination.

  5. 5

    Rotate the key to its original position and remove from the lock. Your new combination is set.

    Model 643D

  1. 1

    Set the lock to its default combination (0-0-0-0), or--if you've changed the lock's combination before--to its current combination. Pull open the lock.

  2. 2

    Turn the shackle (the U-shaped metal loop whose free end connects to the main chamber to "lock" it) 180 degrees, so the shackle's free end is as far away from the main chamber as possible. Press the shackle down.

  3. 3

    Hold the shackle down while you line up the numbers for your new combination.

  4. 4

    Release the pressure on the shackle and lock it. Your new combination is set. Mix up the numbers on the lock so that your combination isn't showing.

    Models 1520D/1523D/1524D/1534D

  1. 1

    Open the lock using the manufacturer's default combination, or using your current combination if you're reset the combo before.

  2. 2

    Remove the shackle.

  3. 3

    Take the spring-loaded metal end cap off the lock. This will allow you to slide off the four or five (depending on the model) combination dials; some dials have all letters, some are all numbers, and some have a combination of both.

  4. 4

    Slide the combination wheels back onto the lock, in the order of your desired combination. Double-check that the desired numbers or letters line up with the "Master" logo on the lock's main chamber.

  5. 5

    Replace the metal end cap, close and lock the shackle, and scramble the combination wheels. You have reset your combination.

Tips and warnings

  • Combination Master Locks that do not come with the "Set Your Own Combination" option cannot be reset. The combination installed by the manufacturer is the only combination that will work on these locks.
  • If you've lost your reset tool (the small key described in Section 1, Step 2), Master Lock advises you to ask in a hardware store for Master Lock part number K175.
  • For instructions on resetting the combination on other Master Lock "Set Your Own Combination" models, visit the company's Frequently Asked Questions page (see Resources section).
  • Master Lock warns users that its locks cannot be reset unless they are in the open position. To safely store your Master Lock's combination, use the company's free storage website, Master Lock Vault (see Resources section).

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