Me. Stat. tit. 26 § 954
If in the agreement provision is made for a method of naming or appointing an arbitrator or arbitrators or an umpire, that method must be followed; but if a method is not provided, or if a method is provided and any party to the agreement fails to follow that method, or if for any other reason there is a lapse in the naming of an arbitrator or arbitrators or umpire, or in filling a vacancy, then upon the application of either party to the controversy the court shall designate and appoint an arbitrator or arbitrators or umpire, as the case may require, who shall act under the said agreement with the same force and effect as if the arbitrator or arbitrators or umpire had been specifically named in the agreement; and unless otherwise provided in agreement, the arbitration must be by a single arbitrator.
26 M.R.S. § 954