I spun the iNCal (currently installed version) at a low speeds to see if low speed operation shows the same vibrations that high speed operation does (see 67207). Even rotating at 1 Hz shows a large increase in signal in the accelerometer (H1:PEM-EX_ACC_BSC9_ETMX_Z) around 200 Hz. 7 Hz shows an order of magnitude increase between 100-300 Hz. The 0 Hz spectrum is with the iNCal powered but a set speed of 0 Hz. 

The lesson is that the iNCal will inject broad band noise in the strain readout even at very low speed operation.