Carefully pull out the fan.

Note: replacing the fan is highly reccomended

Optionally you may clean the fan with Air + Q-Tips. To remove the blade turn the fan over and gently pull the fan blade from the housing.

If the fan is no longer operational, it may be possible to temporarily repair it by removing the fan blade and put a small amount of WD-40 on the pinion shaft hole the fan rotates in. A toothpick is a good applicator. Do NOT contaminate the motor area with any of the dust/grime that has accumulated.

Insert the fan blade and move the blades with your finger. It should spin freely and cog to a stop. Again this is a temporary fix!