You are probably on to something there Nods, it does sound like the green gun is either not firing, or it is not firing as much as it should be, it could also be caused by the red gun saturating. To bew certain, would you say it looks like a pinkish, purple haze or like everything has been washed in the pinkish, purple hue? If so, then I'm pretty sure it is one of those two problems. It could also possibly be a problem with the gun alignment, some newer monitors do not have any way to adjust this, but others do, you would still have to go inside, which I wouldn't recommend unless you know what you are doing. There are extremely high voltages in there, just like in a TV. Is the monitor still under warranty, if so have them fix it.