That is the old wig wag
style washer. The motor
travels in one direction only. To do the wash and spin they implement a dual solenoid mounted on the transmission which constantly moves while the tranny main pulley is turning. This wigwag
provides the motion when the timer
activates solenoids which yank up shift pins connected to shift rods with slots stamped into them. As the shift pin gets into a slot it moves the gears inside the tranny and also yanks open a flap on the pump
. The noise you might be hearing unfortunately is something within the tranny itself. Keep it as long as you can. New washers are not worth a plug nickle these days. I would spend my money getting that puppy repaired. Indestructible reliability.