Abstract: Disclosed is a ball cleaner for a screening machine in which the ball cages are presented by a molded plastic insert having integral intersecting longitudinal walls and cross walls. The weight of material being screened on the screen which overlies the insert is not carried by the insert but rather by a separate support beneath it. The support comprises a peripheral frame and joists within the frame which directly underlie at least the longitudinal walls of the insert. The insert completely isolates the frame from the erosive action of the cleaning balls and can be replaced separately from the frame.