The present disclosure is directed toward a diagnostic method for a spindle arm of a machine. The method includes rotating the spindle arm of the machine at a first rotational speed, and acquiring, from an accelerometer, data indicative of a vibrational response of the spindle arm operating at the first rotational speed. The accelerometer is disposed along the spindle arm. The method further includes converting the vibrational response to a frequency based response to obtain a first frequency response, determining whether an amplitude of the first frequency response exceeds a diagnostic threshold, and performing a designated correction on the machine in response to the frequency response exceeding the diagnostic threshold.