The timing pulleys feature two grub-screws for locking the gear on to the stepper motor shaft. Ensure that one of the two screws is aligned with the flat section of the stepper motor shaft as shown.

When installing the grub screw, some users recommended that you use a thread locking compound (typically Locktite Blue or similar) on the threads. This is completely optional but could prevent the screws from loosening over time and causing print problems.

Align the top face of the pulley with the top face of the stepper motor shaft as shown in the second photo. It will be offset approximately .5mm from the end of the shaft. This is required for proper belt alignment once the stepper is installed in the next step.