How To: Clean Your Dishwasher
Remove and clean the filter. Soak in warm, soapy water for 10 minutes, than replace.
Place a cup of plain vinegar in the soap compartments and the remaining on the top rack of the dishwasher. Using the hottest water available, run the dishwasher through a cycle. The vinegar will help to wash away the loose, greasy grime, sanitize and help remove the musty odor.
Next, sprinkle a cupful of baking soda around the bottom of the tub and run it through a short cycle. The baking soda will help freshen and remove stains.
Repeat every six months.
I use Bosch Top Control Dishwasher. If you are looking for an upgrade, I highly recommend it. The quietest (if it wasn't for a red light indicator I wouldn't know it is running) and most efficient I have ever had.