What do I do if I cannot get the required 180 degree rotation of the Step Change Key to complete a rekey?

You will not be able to complete a rekey if you cannot achieve the required 180 degree turn (half way around) with the Step Change Key

To complete a rekey when you cannot achieve the require 180 degree turn (half way around) with the Step Change key, you will need to utilize the Control Key to remove the core from the housing.

Once the core is removed, you will be able to achieve a 360 degree turn with the Step Change key to ensure the rekey is completed properly.