How is the source connected is it composite by that I mean is it connected by separate leads marked Red Blue And Green? if So check these leads and make sure that they are seated properly into the correct slots.
My TV is green when viewing digital TV but was fine on analogue and also OK when using PS2/3 for games or viewing DVDs so there can't be anything wrong with the tube itself. It has always been like this but more of a problem now the analogue has gone. It's a bit hard watching F1 races when you can't tell the colour of the cars!! Help!!