Mo. Rev. Stat. § 435.390: Change of award by arbitrators.

On application of a party or, if an application to the court is pending under section 435.400, 435.405 or 435.410, on submission to the arbitrators by the court under such conditions as the court may order, the arbitrators may modify or correct the award upon the grounds stated in subdivisions (1) and (3) of subsection 1 of section 435.410, or for the purpose of clarifying the award. The application shall be made within twenty days after delivery of the award to the applicant. Written notice thereof shall be given forthwith to the opposing party, stating he must serve his objections thereto, if any, within ten days from the notice. The award so modified or corrected is subject to the provisions of sections 435.400, 435.405 and 435.410.