Master Lock 643D Series Programming Instructions
Note: 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 90 degree (1/4 turn) so notch on shackle is aligned with notch in lock body.
3. Press and hold the shackle down.
4. Set the dials to your own combination by lining up middle of numbers with red stripe.
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!