My Panasonic CRT 33AK10 has started to develop colour staining. It all started in the corners of the screen and then occasionally along the edges. I know this can happen by placing speakers or magnetic devices nearby the tv, but this is not the case in my set up. After calling out a service engineer today, he came along and corrected it using a massive coil and waving it around the screen. Well it all looked good earlier on but now once again after turning on the telly tonight the corner has begun to stain ? What could this be ?