High temperatures from the sun, snow and ice, road oils and other chemicals in windshield washer solvents can damage the rubber wiper refills, which should be replaced about twice a year or anytime the blades start to streak or chatter. In order to prevent streaks, dirt, tree sap and road tar will damage your wiper blades, and you should always keep your windshield and wiper blades clean. The washer fluid may not be enough and the advice to wash it with a commercial glass cleaner at least once a month will do wonders. You should also wipe the rubber blade of the wiper with a wet rag. When the blades are cracked, broken or torn, they are to be replaced right away. The replacement intervals will vary on how much it is used. However, ozone deterioration usually limits the life of blades to about a year. If the wiper pattern smears, streaks, or the blade chatters, they should be replaced because it makes sense to replace wipers in pairs. In general, if the wipers are just not cleaning, it means the refill is not cleaning. Normally, only if the blade and arm are damaged, would a replacement be required. In order to replace the refill, raise the wiper arm off the glass. Next, depress the release lever on the centre bridge to remove the blade. Once done, lift the tab and pinch the end bridge to release it. After that, slide the end bridge from the wiper blade. Finally, install a new element and ensure the tab on the end bridge is down to lock it in place. There are different types of refills including Trico with a release button, Anco with metal tabs that unlock when squeezed and polycarbonate types that use a locking lever. The plastic backing strip on a Tridon refill can be removed by pulling up and twisting counterclockwise. No matter the refill type, make sure all frame claws engage the refill and that there is no part of the metal frame contacting the windscreen before working the wipers.