The wiper blade is like a little stationary windshield wiper next to the printhead capping assembly (where the printhead parks) on the papers side of the capping assembly that keeps the printhead clear of gunk by wiping across the printhead moves across it. In the service manual for the Epson 3800 it says when the printhead parks, the pump motor raises the capping assembly so the cap seals the printhead (to keep it from dying out). The pump motor also moves the wiper blade into the printhead path when it does this. So I am wondering when the wiper blade actually wipes across the printhead. I am guessing it must be when the printhead unparks and begins to start the print cycle, but I don't really know.