You will notice as time goes by that the inside of the scanner glass gets dirty. The good news is that for this scanner at least, cleaning the glass is really easy.
Firstly remove the scanner lid by unplugging the power cable for the light and then sliding the scanner lid off. Inside each of the two rectangular slots you will see a screw, simply take this out and then you need to push the top of the scanner forward, from back to the front and you will be able to get it out.
Cleaning is now simply a matter of wiping the glass with glass cleaners, putting the top back and screwing it up.