2. In cases where the Employer believes that an employee's job performance has become unsatisfactory, such as when an employee is believed to be careless or excessively absent or tardy, the Employer will notify the Union in writing of such belief and the Union and the Employer shall cooperate in investigating the matter and taking corrective measures, if warranted. If the Employer contemplates severe disciplinary action beyond a reprimand, then the Employer will notify the Union in writing of such belief and the Union will promptly acknowledge, in writing, receipt of such notice. The Union need not acknowledge receipt of simple warnings or reprimands in which the Employer does not state that severe disciplinary action is contemplated. No warnings or reprimands shall be considered for purposes of disciplinary action after twenty-four (24) months from the date of the warning or reprimand