A method of determining variations in operating characteristics of a mechanical system having a rotatory mode of operation and bearing balls entrained within a bearing balls recirculation system. There are provided the steps of first monitoring operating impulses generated by the mechanical system during a first interval of operation; first analyzing the operating impulses obtained during the first interval to determine the intensity and frequency of the operating impulses; first correlating the operating impulses obtained during the first interval to corresponding angular positions of the rotatory mode of operation; and first producing a first record of the intensity and frequency of the operating impulses obtained during the first interval correlated to the corresponding angular positions of the mechanical system. The health of bearing balls within the recirculation system is determined by monitoring the vibration characteristic of the recirculation system, which is correlatable to the specific bearing balls.