un-fasten the top cover
Begin disassembly only after completing steps 1 through 6
You are about to expose the interior of the scanner to the dust of the outside environment. the scanner is very sensitive to dust; any dust particles that get into the carriage head can cause streaks in the scanned image. Minimize the time that the top cover is off by having all the cleaning materials ready. Also be sure to disassemble your scanner in a clean environment.
7Using a Phillips screwdriver remove the four screws from the bottom of the scanner. See the following illustration for the location of the screws.
location of the screws
8Holding the top and bottom cover together, turn the unit back over so that the glass side is facing up.