Machine does not want to agitate but spins fine

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Brand: Maytag washing machine
Model Number: A8520
Main Symptom: Machine does not want to agitate but spins fine.
What happens & when: If one rotates the pulley in the agitate direction it is very reluctant but with force will move. Once moved it will do a load of laundry before seizing again. I have drained the orbital transmission and all parts look good. The input shaft from the pulley moves freely. The only part that does not move freely is the agitation shaft. I have bought Whirlpool WP6-0A57420 Washer Agitator Seal Assembly Part as that is the only place I can see that would cause the agitator shaft to bind. I have also removed the spring clip on top of the metal washer on top of the agitator seal. My question is how does one remove the old seal from the machine? I have looked for videos. So far I have not found any videos for this vintage Maytag covering this job.

Error Code (if any):None
Parts or tests already tried:
Photos / video link: