How to Reset a Master Lock
To reset a Master Lock with a precision dial, open the lock and turn the shackle to access the shackle hole. Next, insert the reset tool and rotate the dial clockwise 3 times to clear the old combination. To enter a new combination, turn the dial right and stop on the first character, then do one full rotation left, passing over the first character and stopping on the second character, before turning it to the right to stop on the third character. Finally, remove the reset tool and return the shackle to its original position!
Open the lock using the old combination. Once you open the lock, turn the shackle off to the side so that you can access the shackle hole. If you do not have the old combination to the lock, you will not be able to reset it. If this is the first time you are using the lock, use the preset combination. This will be listed on the packaging material that came with the lock. Insert the reset tool into the shackle hole. The Master logo at the top should be turned to the side to face the shackle of the lock. Make sure to push the tool all the way in. The reset tool is a long stick with a rounded top that says “Master” on it. This came with the lock when you bought it. If you do not have this tool, you will not be able to reset the lock. If you lost your reset tool, visit your local hardware store or locksmith. They may be able to order you a new one. Turn the reset tool so that the Master logo is facing you. You can turn it in any direction. If it won't turn, try pushing in the reset tool farther. It should turn easily once it is in all the way. Rotate the dial clockwise 3 times to clear the old combination. This will ensure that your new combination works and that the lock isn't still set to the old combination. You must do 3 full rotations, ending on the same numeral that you started on. Enter your new combination. Choose 3 letters or numbers for your combination. To enter a new combination, turn the dial right and stop on your first letter. Then do 1 full rotation left, passing over the first letter and stopping on the second. Then turn it right and stop on the third letter. Remove the reset tool to lock it. Turn the reset back to its original position with the Master logo facing the shackle. Pull it up to remove it. Return the shackle to its original position and press down on it to lock it. Your lock has now been reset. Write down the combination in a safe place. You may want to put it in a journal, on a post-it note near your desk, or in a password wallet. Master Lock offers a secure online system to save your combinations called Master Lock Vault. Open the lock using the old combination. Squeeze down on the shackle twice before entering the combination. This will clear the lock. If this is the first time you are using the lock, you can find the old combination on the packaging materials that it came with. If you do not have the old combination, you will not be able to reset the lock. Use a pen or pencil to flip on the reset lever. The reset switch is located on the back of the lock. When it is off, the switch will be on the bottom of the lever. If it is on, it will be on the top. Press up to turn it on. If the lock is brand new, there will be a sticker covering the lock. Peel this off to find the switch. Squeeze down the shackle twice. This will clear the lock of your old combination so that you can enter a new one. Once you have done this, pull the shackle up again. Enter a new combination by pushing the dial up, down, right, or left. Your combination can be as long or short as you want it. You can use any combination of up, down, right, or left as you want. When you are done, push the shackle back down into the hole to lock it. Keep a steady pressure on the dial as you enter in the new combination. Do not lift or stop your fingers as you work or it may record the wrong combination. Flip the reset switch back down with a pen or pencil. It should remain in the off position until you need to reset the lock combination again. Save the combination in a secure location. You might write it down on paper or save it in a Word document. If you want extra protection, you can use Master Lock's Vault program, which stores combinations online for free. Enter the old combination to unlock it. Line the numbers up with the circles on the front of the lock to open it. If the lock is brand new, the factory combination is 0-0-0. Once you enter the lock, pull the shackle up to open it. Pull the dial up and turn it 90 degrees counterclockwise. You should see a small notch in at the end of the shackle. This should align perfectly with a notch in the body of the lock. Push the shackle down and turn it another 90 degrees. Keep going counterclockwise. The shackle should be on the opposite side of the lock as it was when you began. Enter in a new combination. Turn the three dials to whatever you want the new combination to be. Start with the top dial and work your way down. Turn the shackle back 180 degrees. It should now be at the same position that it was when you first opened the lock. Press it down into the body of the lock. Turn the combination randomly to lock it. Store the combination in a safe place. You may not be able to open or reset the lock again if you forget the combination. Write down the combination on a piece or paper or save it to an app, such as Apple's Password Wallet or Master Lock's Vault. Identify if your master lock has a serial number. A serial number is 6 digits. If there are only 4 digits, it is a date code and not a serial number. The serial number may be located on the back or bottom of the lock. If you have a “Set Your Own Combination” lock, you cannot retrieve your lost combination, even if you find a serial number. This is because you set the combination and not the company. For security purposes, newer Master Locks may not have serial numbers. If you cannot find the serial number, you cannot retrieve the lost combination. Bring the lock to an official distributor or retailer. You can take the lock back to the same retailer you bought it from. They may charge a fee to retrieve the combination; this cost will depend on the retailer, as Master Lock does not charge. Ask them to call Master Lock on your behalf. Master Lock will ask them to verify your identity before giving them the combination. The lock cannot be attached to anything for this to work. This means that you cannot bring in luggage or a bike with the lock attached. Call a locksmith instead. Fill out a notarized lost combination form instead. You will need to provide your name, address, and the lock's serial number. Before sending the form, you must have it notarized by a notary public. Notaries can be found at banks, law offices, and libraries. You must bring official ID, such as a passport or driver's license, to the notary with you. You can find the form here: http://content.masterlock.com/masterlock/resources/documents/pdf/lost_combo_form.pdf Mail the form to Master Lock Warehouse, 24 North Free Port Drive, Nogales, AZ 85621. You will receive the combination within 4-6 weeks. 
Open the lock using the old combination. Insert the reset tool into the shackle hole. Turn the reset tool so that the Master logo is facing you. Rotate the dial clockwise 3 times to clear the old combination. Enter your new combination. Remove the reset tool to lock it. Write down the combination in a safe place. Open the lock using the old combination. Use a pen or pencil to flip on the reset lever. Squeeze down the shackle twice. Enter a new combination by pushing the dial up, down, right, or left. Flip the reset switch back down with a pen or pencil. Save the combination in a secure location. Enter the old combination to unlock it. Pull the dial up and turn it 90 degrees counterclockwise. Push the shackle down and turn it another 90 degrees. Enter in a new combination. Turn the shackle back 180 degrees. Store the combination in a safe place. Identify if your master lock has a serial number. Bring the lock to an official distributor or retailer. Fill out a notarized lost combination form instead. 