Question Vizio E55-F1 Dim

[Mason32800]

I have a Vizio E55-F1, got it in 2018 so obviously out of warranty. The upper left corner is always dimmer than the rest of the screen, and it is intermittently much less dim. Any thoughts? I’ve done everything software wise I can think of and that Vizio has said. What you see in the pictures is what happened when I see the tv being much less dim, and then lightly knock on that corner of the screen to make it brighter, which works.

https://imgur.com/a/rXfMM55

View: https/imgur.com/a/rXfMM55