Upper Agitator Not Agitating

From the central column, pull off the fabric softener dispenser (of course, with the machine off). Reach in and pull out the seal (looks like a diaphram). Using a socket, undo the bolt and pull out the plastic ratchet assembly. I found the 4 dogs in bad condition, ordered them, and received them in a couple days. Replace the old dogs and reassemble. Only the bolt requires a tool. Much simpler and cheaper than I had anticipated.