Testosterone levels in a patient predicts whether or not the patient is likely to recover sexual potency following radical prostatectomy. The electrical rotating coring apparatus comprises a base member, a manakra dock, a securing ring, and a conventional manakra. Each of the outputs is demodulated and filtered by a demodulation filter having a demodulation filter bandwidth. The corrective value thus calculated is subtracted from the current control, determined by taking into account other parameters, to give a corrected control current, which gives to rise to an attenuation in the vibrations transmitted to the steering system and the steering wheel by acting on the servo steering.