What cause green picture on the CTR, how can the problem be solved?

How can it be retained to its majority colour?


Answer:

A dying CRT in which the green gun is effect causes this symptom. Temp solution, angrily bang the monitor from the sides and the commonplace color should come in.

Long residence solution would be to replace the CRT or looking at the price, replacing the monitor itself.
The green color gun on the monitor has malfunction, take it to the repair shop.
CRT is probably on its process out but you can try unplugging/replugging the cable. If problem is a dry solder joint, a transient fix can be via a hard clap on both sides at like peas in a pod time.