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How to Change a Master Lock, Padlock and Combination Lock

It is easy to change the combination on most Master Lock products.
Combination lock set to 2008 image by palmer530 from Fotolia.com

It is easy to forget the combination to a lock. Fortunately, Master Lock offers a way to change the combination on most of its models. This tutorial is specific to one of the most common Master Lock padlocks, model 646, and similar versions. Within 30 seconds, anyone can reset the numeric code.


Model 646 is the one of the most common Master locks. There are different methods for changing combinations on a lock, but this process is the most recommended and will work on model 646 and many other models. For information on how to reset the combination on a specific, yet different, Master lock, please refer to Resources.

Open the Master Lock.

Rotate the shackle approximately180 degrees so it is parallel with the body of the lock.

Push the shackle in, as though you were closing the lock, but the lock will not close because the shackle is parallel to the body.

Set the new combination by holding down the shackle while adjusting the metal digits to a desired code.

Release the shackle, and the new combination should be set. Be sure to test the Master lock before locking it on to an item.

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