It might be something as simple as a loose or corroded connection where the mainboard connects to the green LCD. You could try pushing down on that connector while the PJ is on and watching the image to see if it changes.
Otherwise it might be a bad LCD or bad mainboard. No real way to tell other than to start replacing stuff. You can even try switching the LCD's around, like the red and the green one, and see if the problem remains the same or changes color. If it stays the exact same, its the mainboard, if it changes color, its the LCD.