Remove 3 Torx screws and pull left hand side of fan forwards to remove cover
Use the metal part of the fan to gently prise the impellor off the spindle of the fan. Note: Impellor may be very stiff, if lubricant is used take care not to damage the fan motor windings behind it.
Remove 1 Torx screw securing the PCB to the fan then gently lift and remove the PCB from the fan.