This is specific problem occur on Cetus MK2 machine, MK1 and MK3 Cetus do not have this issue.
The problem is due to the homing mechanism cannot be triggered. The result is continuous search of homing point of the axis, which is chattering of the axis.
This is caused by slight dimensional change of the machine's axis.
You can solve the problem by adjusting the adjustment screw on top of the Z axis by turning it for 1/4 turn on either direction.
For X and Y axes, you can use the stickers included in the package to calibrate the homing.
While MK1 and MK3 use limit switch for homing trigger. MK2 machines use a complete different method. This innovative mechanism take advantage of the waveform change of electric current during the stalling of motor when the axis endpoint is reached. However this mechanism is not continuous all along the axis, but the sensitive region is intermittent.
Therefore after some use of the axis may have some slight dimensional change which result in the endpoint not able to be detected. This can be solved by adding spacer sticker to X or Y motor (side face linear bearing) or slightly turn the screws on top of the Z-axis.