You will need to disassemble the HP Officejet G85 to clean the glass on the scanner. If you notice poor scanning quality or get a "Scanner Failure" message, the glass is dirty and needs to be cleaned. Cleaning the glass will produce better scanning results and prevent you from receiving error messages. Before you take apart the printer, make sure you turn it off and unplug it.
Turn the HP Officejet G85 printer around and unplug the Automatic Document Feeder, or ADF, cord. The end of this cord looks like a USB and is plugged into the middle of the back of the unit.
Pull up on the cable until it is not hooked onto the back of the printer anymore.
Turn the printer around and lift up the lid of the scanner. HP recommends placing both of your hands on the sides of the lid and pulling up on it. It should stand in an erect position so you can easily access the scanner's glass.
Place one hand underneath the control panel and lift it up toward you so it is now even with the glass.
Push on the hook underneath the control panel and slide the panel to the left. You can find the hook underneath the panel on the right side. HP warns that there's a cable connected to the back of the control panel. It needs to be unplugged before you can remove the top of the control panel.
Unscrew the two screws on the back of the control panel.
Press up on the plastic tongues on the right and left of the scanner. This will release the glass from the scanner.
Place a piece of scotch tape over the opening of the scanner. This will prevent any humidity from getting inside the printer.
Wipe the glass with the lint-free cloth. HP recommends using distilled water to clean any dirt or haze that doesn't wipe off with the cloth. Repeat the steps in opposite order to reassemble the printer.
If your Officejet is still under warranty, return it to HP for service.
Taking apart the printer will void any warranty you still have.