Rotate the black metal ring cover to expose the opening in the housing shaft.
Insert a small hex key (included with the new grinding wheel) or nail to lock the driveshaft. Note: Do not use a hypodermic needle to lock the drive shaft.
Use the large hex key (included with the new grinding wheel) to loosen the screw in the center of the solid grinding wheel by turning it counter clockwise.
Unscrew and remove the used grinding wheel.
Put the new grinding wheel into place.
Thread the new screw in the center of the grinding wheel into place turning clockwise until finger tight. Use the large hex key to tighten.
Remove the small hex key from the housing shaft and rotate the metal cover back over the opening to keep it clear of debris.