How do I avoid centrifuge imbalances in the first place?
Ensure that your work surface is level and firm. Do not use the centrifuge on an uneven or slanted work surface.
At high speeds, a centrifuge can easily become unbalanced if equal masses are not located opposite each other in the rotor:
For fixed-angle rotors, balance your tubes according to their weight. Load the rotor symmetrically and ensure the opposing tube is not only the same type of tube, but that it is also filled with the same mass.