Holly,
Your probable problem is worn out "dog ears." They (4 of them)are made of plastic, shaped like dog ears, about 1-inch in length each and are located in the agitator cylinder itself. They have small teeth that grip the agititator to make it spin/agitate in one direction. It's an easy and cheap fix (about $5 and 20 minutes of work.) You can order the parts on-line at any website that sells Whirlpool parts. All you have to do is disassemble the agitator from the top down using basic tools and hand-separating of some parts (but, you'll probably need a ratchet wrench with a long reach because the main screw that holds down the agitator is seated pretty deeply in the agitator cylinder.) Once you see the four dog ears, remove and replace them in the same original position they were in. You may want to re-grease them. You can order that, too ($8). Then replace the agitator parts in reverse order. Can you tell I've done this before?? Hope this helps!
Al, June 2007