silencio 850 dishwasher bottom arm doesn't spin?

My simpson silencio 850 doesn't seem to spin the borttom spraying arm. Am I supposed to push it down into the slots or just sit it on top? Either way it doesn't appear to turn. What could the cause be and is there an easy fix for it? Thanks for any help.
Bruce Jackson, February 2006


done
Clean out the nozzles on the spray arm, the end ones in particular are angled to provide the spinning motion as a reaction to the water jetting out.

markus, May 2009
link Click here to see other fixes for Simpson Silencio 850.