Check all of the holes in both top & bottom arms are clear and not blocked. Listen when wash cycle starts after the fill. Can you hear motor running? If you can then does the water spray inside sound strong & loud with no dishes in it? If it sounds weak then there is probably an issue with the internal pump impellor and wash pump will need to be removed & dismantled to find the cause. If wash pump did not start then that raises a whole lot of other possibilities.
Lincoln Appliance NZ
January 2012