The NOKIA TV of a friend is out of tune with the colours, the picture is dull and not all colours are properly displayed, green - blue is weak and not stable. This is surely a common problem for an old TV, are there some technical adjustments or replacements to be made?
Sounds like the degaussing positor may have failed. If so, it's a very simple and inexpensive repair. Usually, you will get a blotchy rainbow like effect to the colours, especially around the edge of the picture, if that is the fault.
There are other possibilities but it does sound like the positor's failed. It is usually safety specified, so the correct type must be fitted, but still a simple job.
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Try fixfault.com to fix televisions.