A haymaking machine for windrowing forage includes a frame carrying several rotors connected to carrier arms which are articulated to the frame and which can be moved from a work position into a transport position. A first signal producer produces, based on reception signals generated by the antenna elements, first signals which are equivalent to signals generated by antenna elements arranged at first intervals d1, d1 being an integral multiple of d. During molding, a portion of the frame forms a key that freezes in or around the frame retention feature. The invention also relates to kits for use in such method.