if its every time the same pixel which is dead, it can not be the cable. but a try still does not hurt.
ok, thanks... I have not looked at the rest.
@FatAlbert
If your Pixel is dead, you cant revive it. but if its a stucked pixel you can try to stimulate it.
Stucked pixels are pixels whose inputlines are interrupted or clogged. with a bit of luck you can change that but mostly you can do nothing against it. one path would be the stimulus with colour, the other and much more dangerous path would be a circular massage around the pixel... but you can quickly destroy even more and I would advise against it if it is only a single pixel which is dead.