replacing the power cord is easy I had to do it a few years back when my reefkeeper decided to go nuts and fry the end of one of the cords. You can get the replacement cords from Home Depot or Lowes. You will take the unit apart, disconnect the current power cords, and attach the new cords. If I recall correctly the wires are connected to the unit with the twist type of connectors. As for the fan, I never had to do work on those so I can't help there unfortunately.