Tom is right, on the upper-end models, there was a cup inside the top of the agitator (similar to Frigidaire) that held the bleach until the agitation started and the cup was flooded and overflowed, dispensing the bleach. The agitator "cap" had a perforated center where the bleach was poured in, probably prior to loading the clothes. Similarly, the ring dispenser "Fountain" pictured directly above dispensed when the pumping of the agitator began and water flooded the ring.
Out on the Sacred Appliance burial grounds in South Dakota, there were many Hotpoints with the various agitators and dispensers. We should have taken more of those parts!