A motion to amend findings or conclusions or to make additional findings or conclusions shall be served not later than fourteen (14) days after entry of the judgment, and if granted the court may amend the judgment accordingly. The motion may be made with a motion for a new trial pursuant to Rule 807. When findings of fact are made in actions tried by the court without a jury, the question of the sufficiency of the evidence to support the findings may thereafter be raised whether or not the party raising the question has made in the district court an objection to such findings or has made a motion to amend them or a motion for judgment. No party may assign as error the lack of findings unless the party raised such issue to the trial court by an appropriate motion.