Take either one of the arms loose at the base, 13mm wrench, them hit the switch and let them cycle, and "park" then tighten the one you loosed, making sure you align them according to the factory manual. I don't know the age or manufacturer of the wiper blades, but, I'd in vest in a good quality set like Bosch, or even Triple-edge. It's also a good idea to hand clean your windshield often, even though it may not look dirty, it keeps the minute oil and grime off that makes the wipers "chatter". The least that you could do to reduce the chatter is to get some extra fine sand paper and fold it in half, and run it over the wiper blade edge. Keeps them up to snuff.
P.S. Some of us have even used that "invisible wipers" stuff you can get at parts houses and if you keep it on the windshield, you don't need your wipers that much, because that stuff really works, especially on the much angled GT windshield.