Grey patches on Sony Bravia TV

[Radio Fixer]

Set about 7 years old and it has been faultless so a good buy.  But now areas of the picture have a dark tint on light subject matter, like tennis hard courts .

Its an LED type and I understand very or next to nothing about them but believe they have back lighting or is that only the plasma ones.  Is it fixable by me?  Not worth spending money on a repairer, rather put that to a new one as the tech has moved on a lot since.

Looking at new ones what a minefield it is:  Sony make a huge variety of models ...  Do I need 4K?  Maybe Virgin Media cable will be doing some progs in it?

thanks Gary