Changing the rubber is important ;) But really a sharp crisp squeegee rubber leads to a cleaner more streak free job. Missing in this is explaining you can flip your rubber to use on the other side. Do that before tossing it out. The rubber will wear down quicker in hotter conditions and when your are cleaning super dirty windows and when the windows have crappy or older frames. I change mine about every two or three days. Sometimes more depending on the circumstances.
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