Product review (5 stars): Genuine Whirlpool Part - Repairs Agitator Function
Purchase this part if the top section of your agitator is no longer functioning properly. You'll know this by observing the wash cycle and noting your clothes are not rapidly agitating and/or you can spin the upper agitator assembly clockwise and counter-clockwise by hand with no resistance.
Failure occurs when the original dogs/tabs disintegrate and no longer engage the upper agitator.
Disassembly is pretty straightforward, as is the repair. If you don't know how to perform this procedure, a simple Youtube search will turn up helpful instructions.
These are genuine Whirlpool replacement parts, therefore order with confidence.