Because wiper blades are always in contact with the weather, it's wise to clean off debris from the road and salt every few months. Wipe the wiper blades, arms and windshield with a sponge or cloth together with a light detergent or cleaner that does not scratch. Replace your wiper blades if you find streaking or smearing has not gone away. The wiper blade ought to work smoothly over the windshield, both in one direction and in the opposite one, with a slight rollover over the center when it reverses. A wiper blade that misses some areas or produces a vibrating sound could be due to flexible wiper insert or a weak spring. If wiper blades are less than a year old and their spring is enough, but they chatter, it may be because they do not lie over the center, so you need to adjust the wiper alignment.