I think your talking about the coupling inside the agitator.
I'm not sure which machine you have, but the method is the same.
4lb sledge and appropriate sized rod, like a 3/8 craftsman extension rod. Put through hole and set on the lip of the agitator and start banging away. rotate as you do it. be patient.
On the older machines I made the hole too large for the bolt that attaches the agitator so off to the ship's store for a washer and stainless bolt.
If it's the model that recirculates the water while agitating then it's a wonderful and powerful machine. | 
Need To Replace Agitator Coupling 
