I was having the same problem I think. The washer would spin fine but the agitator wouldn't agitate. I called a repair man and it turned out to be a very simple solution. He pulled the agitator off. Jerk very hard straight up and under it is a plastic hub held on with a bolt. This hub has plastic teeth inside it which were stripped. The replacement part was about $6.00 and had I know this I could have save myself $55.00 for the service call.
JIm
February 2008