Section 3. If the arbitration agreement provides a method of appointment of arbitrators, such method shall be followed. In the absence thereof, or if the agreed method fails or for any reason cannot be followed, or if an arbitrator appointed fails or is unable to act and his successor has not been duly appointed, the court on application of a party shall appoint an arbitrator. An arbitrator so appointed shall have all the powers of an arbitrator specifically named in the agreement.