2. The players draw the beginning at the top cushion. The two white balls must be in motion before one of them reaches the top cushion. If this is not the case the draw will be repeated. The player who causes two times such a repetition loses the choice to begin. It is not admitted to effect the cushion draw by a stand-in.
So as Jim said, it is a do-over unless one of the players is responsible for a second problem. An old-time US champion recommended waiting until the opponent's ball bounced so as to get more info about rail conditions. That is illegal now.