The present invention relates to a rotatable work tool assembly comprising a rotatable body (13), a fixed holder for the body, a work tool (22) mounted on the body, a pivot pin (21) extending from the holder, and a recess (20A) within the body adapted to receive the pivot pin so that the body can rotate about the pivot pin relative to the holder and the work tool can move into a selected work position. According to the invention the assembly is characterized in that it comprises biasing means for applying a biasing force to the body in a direction along a line extending from the axis of the pivot pin to the work tool for all positions of the body as it rotates so as to tend to prevent any movement of the body relative to the pivot pin along the line due to spacing between the outer surface of the pivot pin and the inner surface of the recess.