A frequency clue and incomplete evidence

A fictional monitoring report records a once-per-main-rotor-revolution vibration during a defined test condition. It provides no completed tracking measurement, blade mass-moment record, spinner or shaft inspection, sensor calibration check or approved correction calculation. A learner proposes adding weight to a convenient blade location because the label seems familiar. Another asks for the actual diagnostic and balance procedure before identifying a cause or correction. The task concerns evidence quality rather than performing a rotor run. It supplies no allowable vibration amplitude, balance-weight amount, attachment location or release authority. A sound answer treats the frequency as a useful clue, retains its main-rotor reference and distinguishes tracking, mass distribution and other possible sources before claiming that a correction is justified.