How do I clean the interior of the dishwasher to remove hard water buildup?

Make a paste with powdered dishwasher detergent on a damp sponge and clean the interior, or use liquid automatic dishwasher detergent with a damp sponge. You can also perform an occasional white vinegar rinse by placing 2 cups (500 mL) of white vinegar in a glass or dishwasher-safe measuring cup on the bottom rack and running a complete wash cycle without detergent. Do not use any cleanser other than dishwasher detergent, and always run a normal cycle with detergent after cleaning. (Pages 17, 19)