Rotate the black metal ring cover to expose the opening in the housing shaft.
Insert a small Allen 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 as it can snap and break off.
Insert the grinding wheel removal tool around the grinding wheel fitting it between the wheel and the guard on the right angle shaft. Rotate the grinding wheel counter clockwise to loosen. Alternately a very small sized vice-grip plier can be used to grasp the top of the grinding wheel to loosen.
Unscrew and remove the used grinding wheel.
Put the new grinding wheel into place. You will need to use a washer (included with the new grinding wheel) on the newer PowerFloat attachments in order to ensure the diamond grinding wheel surface is above the edge of the guard. On older models you may not require the washer.
Thread the new grinding wheel into place turning clockwise until finger tight.
Remove the Allen key from the housing shaft and rotate the metal cover back over the opening to keep it clear of debris.