F
If this occurs in every input and with every compatible machine i have bad news...
Probably this is a broken line of LEDs To fix that you may change your internal display, which is not cheap...
Well, you are right and i havent though about that.
What if only one member of the team did it for 6 ~ 8 hours and the other one has to continue his work for another 6 ~ 8 hours ?.