I have a problem with my 4k tv. I can see a white bar on my screen when I use a greyscale test and aggravate the effect. I don't know if this is called banding, because I thought banding was only dark in colour. Also, I don't think it's possible to exchange my television, so can I maybe change the pressure of the screws or try to get it repaired? Any tip would be helpful, Thanks in advance!