Lubricate the Fan Motor Bearings

Safety Warning: Always unplug the fan from the power source before performing any maintenance.

1. Access the motor housing by removing the protective covers or screws according to the manufacturer's manual.
2. Locate the motor shaft and the oil port or felt wick surrounding the bearing assembly.
3. Apply 2-3 drops of SAE 10 machine oil directly into the oil port or onto the felt wick. Avoid using WD-40 or other solvents, as these are not long-term lubricants and can cause the bearings to seize.
4. Manually rotate the fan blades several times to ensure the oil is evenly distributed throughout the bearing housing.
5. Reassemble the fan housing and plug the unit back into the power source.
6. Verify the repair by turning the fan on to its highest setting; the unit should now operate silently and reach full RPM without sluggishness.

Sources