FAQs - Master Lock®

Frequently Asked Questions
Question:	How do I change the combination on a "Set-Your-Own" combination lock model #643D?
Answer:	Here are the instructions for changing the combination on you model 643D lock. This lock is preset at the factory to operate at 0-0-0-0. 1. With dials at 0-0-0-0, pull out the shackle 2. Turn shackle counter clockwise 180 degree (1/2 turn) and press it down 3. Continue pressing shackle 4. Set the dials to your own combination 5. Lift and return the shackle to closed position 6. Scramble the dials to lock Note: Be sure to record your NEW combination as you are the only one that knows it! (Try our combination registration site at combolocker.com, a free service from Master Lock!) Note: The lock may only be reset when it is in the open position. If you do not recall the combination the lock is set to, you will not be able to reset the combination.

Here are the instructions for changing the combination on you model 643D lock. This lock is preset at the factory to operate at 0-0-0-0.

1. With dials at 0-0-0-0, pull out the shackle
2. Turn shackle counter clockwise 180 degree (1/2 turn) and press it down
3. Continue pressing shackle
4. Set the dials to your own combination
5. Lift and return the shackle to closed position
6. Scramble the dials to lock

Note: Be sure to record your NEW combination as you are the only one that knows it! (Try our combination registration site at combolocker.com, a free service from Master Lock!)

Note: The lock may only be reset when it is in the open position. If you do not recall the combination the lock is set to, you will not be able to reset the combination.