Got a Roomba? Clean these filthy components right now

I thought I'd been doing a good job keeping my iRobot Roomba 675Remove non-product link clean, carefully pulling clumps of hair off its brushes and wheels and emptying its bin after every cleaning. Little did I know that dust and gunk were building up in places where I wasn't even looking. First, consider the metal charging contacts on the Roomba's base station. When was the last time you gave them a close look--or looked at them at all, for that matter? I sure hadn't, but when I did, I saw that instead of being completely silver, one of the two contacts had a rust-colored ring around it, while the other was almost completely discolored.