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.
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.
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.
Elyse Gibbons started writing in 2006 as a contributing reporter for the "Press-Republican." In 2009 she became an interim managing editor for CNHI Publications, then returned to editorial writing in 2010 as a senior reporter for the "Malone Telegram." She holds a Bachelor of Arts in journalism from Plattsburgh State University.