The arms on the D/W turn by the spray of water from the holes. the holes are directional that is why thay turn take them of and make sure the holes are not blocked. If they are ok. you can look at the way they are faceing to start with then start it and let it run and open the door if they are still in the same place then you will know they are not moveing.there are new D/W that will have a port hole in them like a W/M that will help
J,R, December 2005