Dishwashers are relatively little work when it comes to home maintenance. They only need to be cleaned and inspected a couple times a year. Over time the food particles build up on the spray arm and in the filter. Pre-washing dishes before placing them in the dishwasher will help to prevent the need for additional cleaning. Also, check the tines of the dish racks for damage. Over time the plastic can wear away and leave metal. If you haven’t used the dishwasher in a while a cup of vinegar will help remove any leftover soap film and mineral buildup from hard water. Do not use laundry bleach to clean any parts of a dishwasher as it cause make the plastic more brittle and ruin the door gasket.
To clean the spray arm first detach it and place it in the sink. Use a nylon brush to remove any buildup and clean out the jet holes. Any cleaners used must be dishwasher safe or the plastic could be damaged. A homemade cleaning solution of water and vinegar works particularly well for cleaning the spray arm. If there are any items lodged in a jet, use a stiff piece of wire or a toothpick to poke it loose. A clean spray arm will help significantly to clean the dishes.