Check the video output I/C's/Transistors on the CRT base.
Also try swapping the green cathode with either the blue or red to see if the colour changes. If it doesn't, then either tube base, or tube.
Q: Can you see green with faint green diagonal lines but still see a picture?
or
Q: Is it bright green with lines and no picture?
or
Q: You have a clean looking picture that is green but either red or blue objects don't appear or are black