how to reset a master lock 4 digit
1 Open lock with the factory set or previously set combination. 2  The lock must be set to the current combination, or you cannot reset it. 3  Note: the shackle must be in the open position to reset the combination. 4  Insert reset tool (enclosed in package) in hole on side of lock. 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.