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I would like to find out the procedure for changing out a standard shackle to a 5″ long shackle for a Master Lock Pro Series 6621 Padlock. Both padlock and shackle are brand new, can you help?


Sure! According to the Master Lock instructions, the ProSeries Door Hardware Locks employ a construction technology similar to that used in the Rekeyables. It also allows for a uniform assembly and disassembly technique. Below is the step by step procedure for disassembling this version of padlock. The only exception to this procedure will be the IC version of the lock. For the instructions, see the image below.

  • Use the key to unlock the shackle, A (If key is unavailable you will have to use another method to unlock the shackle)
  • Use a 7/64″ hexagonal wrench to remove the mounting screw located inside the toe side shackle hole.
  • Holding the plug retainer, D, in place, lock the shackle, A, into the padlock body (This relieves pressure on the actuator).
  • Remove the cylinder driver, K, with the cylinder, C.
  • Remove the driver if it did not come out with the cylinder adapter and the cylinder.
  • Remove the actuator, E.
  • Remove the locking ball bearings, B, and shackle, A. Note: For the removing the ball bearings, the shackle must be in both of the holes and just give it a tap on the table. Both bearings should fall out at this point. Change the shackle to the new size and reverse instructions to put it back together.
  • The order may be reversed to reassemble the lock. A light application of assembly grease may be used to hold the ball bearings in place during assembly.
  • If the lock only needs to be re-keyed, it is not necessary to remove the actuator, ball bearings, or shackle.

 Master Lock ProSeries Technical

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