• Before separating front and back assemblies, remove combination tag and write locker number in area designated. This is important!
• Set dial at "0" at red marker. This setting aligns interior parts for easy assembly.
• With dial on "0" at red marker, separate knob assembly from case assembly. DO NOT interchange knob assembly from one lock with case assembly from another.
• With one hand, line up two holes in case assembly, with screw holes on inside of locker door.
• With other hand, insert knob assembly (with red dial marker up and dial at "0") through holes on locker door into case assembly. If units do not fit together flush, turn knob until unit drops into position.
• Place locking nuts on screw bolts and tighten. Lock is now ready to operate on original combination.

WARNING: If electric socket wrench is used, do not exert excessive pressure.

How to Change the Combinations (1630, 1631, 1654, 1655, 1670, 1671)

1. Insert control key and turn it right one-quarter turn. Open door.
2. Revolve dial to the right at least one complete turn, stopping at zero (0).
3. Depress push-button on back of lock case and hold in depressed position.
4. With other hand, turn dial right to number 48. Do not turn dial more than two numbers with button depressed. Then release push-button.
5. Turn dial to the right until you hear click. Then stop. The combination has now been changed.
6. Close locker door. Remove key by turning it one-quarter turn to left, back to original position.
7. Combination has now been changed automatically to next combination assigned. Dial the new combination (see chart for dialing numbers) to be certain that combination has been properly changed.
8. If a mistake was made in following above instructions, dial first combination (see chart). If it does not work, dial next combination, etc., until correct combination to open lock is reached.

IMPORTANT: Make sure the combination change is reported to the lock supervisor so the records can be brought up to date.

Administering Your Built-in Combination Locks
Master Lock built-in combination locks have been specifically designed with the locker administrator in mind. They are quality-built and easy to install. Combinations can be changed in a few seconds. If a few simple precautions are taken, the system will be easy to administer:

• Instruct the locker installer, if not already done so, to install all locks with the serial numbers in sequence and to write the locker numbers on all tags and deliver them to your office. On your combination chart, enter locker numbers opposite the corresponding serial numbers. If the installer should forget to enter some locker numbers, you will find the proper serial number on the back of the lock.
• The name of the person to whom the locker has been assigned and/or the date of assignment should be entered on the chart in the space provided under the original combination. Since some administrators may prefer not to use the chart book as the official record, we suggest a standard 3 x 5 card showing the locker number, the assigned combination, and the name of the user.
• Only one person should have authority to change combinations and must have access to the chart book when changing the combination. Once changed, the new combination should be reported to the office so that your records can be changed.
• IMPORTANT: Your built-in locker locks provide a high level of security and will last many years when properly used. As models vary in functionality, it is suggested that instructions on usage be communicated as part of your administrative procedure.
• GUARD THE CHART AND THE CONTROL KEY! The security of your entire installation is in jeopardy when unauthorized personnel have access to the chart and/or control key.  Make certain both are properly safeguarded.
• Duplicate Control Charts can be ordered either as the standard booklet or on disk in ASCII format. There is a nominal charge per replacement chart. Please submit your request in writing.

Instructions for Opening Built-in Locker Lock Products

1630, 1631
TURN RIGHT two or more whole turns and stop at the first number in the combination.
THEN TURN LEFT one whole turn past above number and stop at the second number.
NOW TURN RIGHT and stop at the third number.
LIFT LOCKER HANDLE.

1652, 1653
TURN RIGHT two or more whole turns and stop at the first number in the combination.
THEN TURN LEFT one whole turn past above number and stop at the second number in the combination
NOW TURN RIGHT to the third number and continue turning right until locker opens.

1654, 1655
TURN RIGHT two or more whole turns and stop at the first number in the combination.
THEN TURN LEFT one whole turn past above number and stop at the second number in the combination
NOW TURN RIGHT to the third number and continue turning right until locker opens.

1670, 1671
TURN RIGHT two or more whole turns and stop at the first number in the combination.
THEN TURN LEFT one whole turn past above number and stop at the second number.
NOW TURN RIGHT to third number and continue turning right until dial stops.
Locker door will open and close freely. To RELOCK, close door and turn dial to LEFT one full turn.

Trouble-shooting Guide

1. Dial jammed, will not turn, or is difficult to turn.

• Splines were not lined up correctly when lock was installed. If the splines are not bent, proper reinstallation will correct it.
• Locker door material too thin.
• Check for "Crazy Glue".

2. Lock will not open using the combination.

• Lock is not set to the combination you are using. Cycle to the first combination, then try again. Then advance to the combination it was supposed to be on and try it again.
• Wrong combination for that lock. Check the chart. Make sure the serial number matches the lock on the door for that locker.
• New Installation - Incorrect dial, switched during installation. Check the dial codes in the chart.
  You may have a left hand lock on a right hand door. Keyway will be upside down. 1652/1653, 1670/1671 can be removed and reinstalled on the correct handed doors. 1630/1631, screws will have to be drilled out to remove and dial assemblies replaced.
• Dialing a half a number off on one or two numbers may cause the lock to stick or not open at all.

3. Lock will not open using any of the five combinations.

• Wrong combination for that lock. Check the chart. Make sure the serial number matches the lock on the door for that locker.
• New Installation - Incorrect dial, switched during installation. Check the dial codes in chart.
• You may have a left hand lock on a right hand door. Keyway will be upside down. 1652/1653, 1670/1671 can be removed and reinstalled on the correct handed doors. 1630/1631, screws will have to be drilled out to remove and dial assemblies replaced.

4. Control key will not open some or all of the locks.

• Check for "Crazy Glue".
• Control key is worn or has been duplicated on a key blank not manufactured by Master Lock.
• Incorrect key control.
• You may have a left hand lock on a right hand door. Keyway will be upside down. 1652/1653, 1670/1671 can be removed and reinstalled on the correct handed doors. 1630/1631, screws will have to be drilled out to remove and dial assemblies replaced.

5. Control key works, but with difficulty.

• Control key is worn or has been duplicated on a key blank not manufactured by Master.
• Incorrect key control.

6. Will not change combinations.

• Button is not pushed in far enough.
• Proper combination change procedure not being used.
• If control key is on a heavy ring of keys, the weight of the ring may turn the key too far, prohibiting the combination from changing.

7. Lock will not open with combination or control key

• You may have a left hand lock on a right hand door. Keyway will be upside down. 1654/1655, 1670/1671 can be removed and reinstalled on the correct handed doors. 1630/1631, screws will have to be drilled out to remove and dial assemblies replaced.
• Locker door material too thick.

8. Lock skips combinations when you try to change them.

• Button is not pushed in far enough.
• Proper combination change procedure is not being used.

9. Dial sticks when retracting bolt on 1654/1655 or 1670/1671.

• Improper door alignment will cause the bolt to drag on opening or prevent bolt from locking. Try leaning against or shifting the door position while operating the lock.

10. Lock sticks when you lift the handle to open the door.

• Try operating the lock off of the locker, in your hand.
• Try operating the locker with lock off.
• Operate the locker with the lock off, but put back pressure against the part that engages the lock.
• Dialing a half a number off on one or two numbers may cause the lock to stick or not open at all.

11. Locker door sticks after you pull the handle up, but opens with the lock off.

• Too much retention on the locking pin, or latch in the locker door may be borderline, or latch exceeds the travel of the bolt on the 1630/1631.

12. Sudden rash of thefts - with no damage to the locks.

• Students presetting combinations or not locking 1670s.
• Students writing combinations on their lockers or giving them out to their friends.
• Missing chart or control key.
• Student watching someone opening their locker and remembering the combination.
• Some of the ventilated, wire mesh and regular box lockers offer poor protection for the spring latch. The 1670 offers better security.

13. 1630/1631 will not lock.

• 1630/1631 bolt has been forced. Usually due to kicking the handle of older style lockers.

14. Combination works, key turns all the way around, but does not open the lock.

• Locker door material is too thick.

15. Control keys break easily.

• Control key is worn or has been duplicated on a key blank not manufactured by Master Lock.
• Incorrect key control.

16. Do not have control keys, know serial numbers, or have charts for a group of built-in locks, locked on lockers.

• Contact Master Lock customer service at 888-878-9952 for assistance.

17. Door will not close (1630/1631) unless you redial the combination so you can lift the handle to close it.

• Automatic locking rod system in the door is worn. Can be corrected by repairing the door or using 1670/1671.

18. If problems persist, contact Master Lock customer service, your local distributor, or your Master Lock sales representative.