A vessel filling machine having a conveyor for conveying vessels to be filled in spaced relation through a filling region in which filling devices engage the vessels from above. In the absence of a vessel in a respective position of the conveyor, the respective filling device will move beyond the normal vessel engaging position thereof to a second position. Feeler elements are located along the filling region for detecting the positions of the filling devices. In the event a complete vessel is absent from a position on the conveyor, the feeler elements cooperate to actuate an instrumentality designed to clear debris from the position from which the complete vessel is absent and in the event the debris is not cleared from the position, the machine stops.