Disposal doesn't chop food well or drain has an odor.

Fill an ice cube tray ½ full of vinegar and ½ full of water. Once the cubes are frozen, put them in the disposal and turn on. Use 2-3 cubes a week for about a month. This will not only sharpen the blades, but keep your drain clean at the same time! (Lemon peels also work well for odors).