Have you tried using a Dishwasher Cleaner which cleans all the grime and fatty build ups in the rotary arms? If not give it a try, I use "Magnum" Dishwasher Cleaner (Aldi Stores usually have it in for a couple of quid - I got a load while on offer for 50p for x2 pack), You'll need to make sure your dishwasher is empty of pots and just follow the instructions on the packet. If that sorts it, great. If not, you may need to remove the lower Spinning Arm and fully dismantle it, not to hard with a screwdriver. and see if it has any problems with it. if that is fine, it may be a blockage in the untake pipe for the water to go through as all dishwashers pump the water through itself and reuses the water inside when washing, then removes the water and adds fresh water to clean with. You may want to google Dishwasher Cycles and your model number to see how it does it. If it isn't the pipe, it may be the pump. I'm not sure how you would go about checking the pump though. I hope this all helps
Rob
December 2013