To remove the rotor from a Hettich centrifuge (Rotanta, Rotina, etc):
- Open the centrifuge and locate the nut at the center of the rotor.
- If your rotor has a plate secured with four screws surrounding the central nut, leave those screws alone. The plate is part of the rotor removal mechanism.
- Using a 5mm hex key, turn the nut counter-clockwise while preventing the rotor from turning with your other hand. The nut will lift the rotor free of the shaft. It might take a bit of torque to break it loose.
- Remove the rotor.
Before reinstalling the rotor, apply a thin layer of grease (Hettich recommends white lithium grease) to the shaft to help the rotor seat tightly and to prevent the rotor and shaft from seizing together.
I also made a video: