Remove the fabric softener dispenser from the agitator. Inside the agitator, is a plastic cap which covers the clutch mechanism - remove this cap, pulling it out by the tabs.
You probably need a new 'agitator dog' kit (< $10). That was my problem. These 'dogs' are cams that flip out and lock the agitator during oscillation. When worn, the agitator becomes weak and works poorly or not at all.
Terry, October 2008