The umpires shall hear cases on a rotating basis. The umpires shall maintain their position until such time they retire, resign, or are in any other way unable to serve in the capacity of arbitrator between the Employer and the Association. Notwithstanding the preceding sentence, either party may strike a permanent arbitrator within 30 days after the expiration of the Agreement and use the process described in paragraph 212.A and 212.B above for selecting a replacement. In such a case, within thirty (30) days, the parties shall request an FMCS panel to determine the replacement. In such a case, within thirty (30) days, the parties shall request an FMCS panel to determine the replacement.