Questions & Support

Key Control Locks

Note: this section is for School Administration only.

Control Chart: Each order of key control locks comes with a paper control chart that contains the serial number and the corresponding combination numbers. A school’s complete charted system is kept on file by dudley®.

Even though a paper control chart is forwarded with each order, you receive said data in an Excel-file by email.

Refer to caption Electronic Control (EC) on our School Order Form under data for cost in relation to the above captioned option.

If you choose one of the above captioned options, make sure you specify the one you are selecting and if by e-mail, kindly provide us with the e-mail address.

For further information, please do not hesitate to contact our Customer Service department at 1-800-227-9599.

Lost Combination Retrieval

Only serialized locks may have the option of combination retrieval. In order for us to be able to provide you with the lost combination number(s), we will require the serial number(s) of the lock(s) in question. However, only records from the last 10 years MAY be available.

For your information, the serial number is engraved at the bottom of the lock or on the back of the lock for the DY1525 or DYA400K.

A) My lock does not have a serial number:

To provide enhanced long-term security, Master Lock has discontinued imprinting a serial number on the lock body on combination locks sold through retail locations. For greater convenience, we encourage consumers to store their combination at our secure website,, which is easy to use and offers 24/7 access. Unfortunately, we are unable to provide combinations for non-serialized locks. Please see examples of a serial number if you are unsure if your lock features one.

B) My lock has a serial number:

Please see examples of a serial number if you are unsure if your lock features one.

Choose from one of the two options below to obtain your combination:

Note: Due to increased security concerns nationwide, Master Lock recognizes the heightened need for additional safety measures. We no longer provide lock combinations in response to phone, fax, or email requests.

1) Visit a Master Lock Distributor/Retailer

  • Bring the lock to a Master Lock distributor or retailer. The lock must not be attached to anything.

    IMPORTANT: If the lock is not brought to the retailer or distributor, we will not release the combination.
  • Ask the distributor or retailer to contact Master Lock for the combination on your behalf and we will validate ownership through them. US distributors may call 1-800-308-9244. Canadian distributors may call 1-800-227-9599.
  • Please note that although Master Lock does not charge for this service, some distributors or retailers may charge a fee.

- OR -

2) Submit a Lost Combination Form

  • Confirm that your lock features a serial number prior to submitting a Lost Combination Form. Please see examples of a serial number if you are unsure if your lock features one.
  • Print out the Lost Combination Form from a Printer Friendly Page or download a PDF file.
  • Have your Lost Combination Form notarized by a Notary Public to prove you are the owner of the lock. You can include up to 6 combinations on one notarized form.

    Note for inmates at a correctional facility: In addition to the Lost Combination Form, you must submit your request on official prison facility letterhead. In lieu of notarization, the Lost Combination Form must be signed by a prison facility official.
  • Submit your form to:
    Master Lock Warehouse
    1600 W. La Quinta Rd
    Suite/WHSE # 1
    Nogales, AZ 85621
  • Once the request is received, your combination will arrive in approximately 4-6 weeks.

Store your combination at – a FREE service from Master Lock! The Master Lock Vault provides a safe & convenient place to store all of your confidential data for quick & easy access from your PC, iPhone, or any other mobile devices!

Phone: 1-800-227-9599


We offer a limited lifetime warranty on all dudley products. Liability is limited to the replacement of our product only. The warranty does not cover damage resulting from mis-use or abnormal abuse.

All defective locks must be returned to us freight or postage prepaid (Collect shipments will not be accepted). Therefore, to reduce and avoid unnecessary shipping costs for locks beyond the guarantee period, we suggest that you first fax or e-mail the serial number of the defective locks to verify if still on warranty. Fax and e-mail address as follows:

Fax: 1-800-229-0081

Once your list has been verified, a Customer Service Representative will advise you which locks are still under warranty and how to proceed. Should defective locks need to be returned to our attention, we will provide you with a RA (Return Authorization) number which is required to be referenced on your school letterhead.


Click the PDFs below to reset your combination.