Simple - the old Panaflow unit was loud and vibrates due to worn out bearings. But don't hope for a silent O2, its still pretty loud.

• Pull power cord (this is the first thing you have to do, if you take something apart!!)
• Pull PSU
• remove the three marked screws

• Lift the base off using your thumb. It requires a bit of force; then flip it open.

• remove the fan screw

• What looks like a rivet isn't one, so don't just snap it off or pull it out. Using a slender object—one that isn't too sharp—you can push the inner section inward, allowing the entire piece to be pulled out without damaging it.

• Unplug the old fan and pull the wires out of the plug.

• cut the wire of the new fan to the right length and press the wires in the old plug. You need some force, doubble check the polaritiy!

• Attach the air guide pieces to the new fan.

• Put the fan back in position
• closeup how the air guide pieces are correctly installed