AS-4000 User’s Guide Maintenance E Remove the backing from the base of the color measurement unit. Remove the entire backing by lifting the hook on the back. F Place the backing on a level surface for cleaning. If paper dust, dirt, glue, and so on, have stuck to the surface that comes into contact with the substrate, wipe them off with a woven polyester/nylon knit cloth soaked in the alcohol for cleaning ink. G After hooking the backing, hold the screws and push the backing up. When you push the screws up you will hear a click. Check that the backing is fixed securely. 77