Purchased a full cam and dog assembly repair kit from AppliancePartsPros.com. Shopped around for this specific Whirlpool replacement part and found cost + shipping was the lowest at this site. The repair took about 15 minutes total and was successful at fixing the problem. Note that the lower agitator was spinning properly - the dogs which grip the splines on the cam assembly were all worn out and no longer keeping the upper column locked with the lower agitator body causing it to spin freely. This part will correct that issue.