My US N64 is RGB modded.
Gave me a good picture for a very long time.
Now it has a slight flicker in the picture, not as system-affecting as my SNES problem but still it drives me crazy and affects my enjoyment of the N64 (if there is such a thing, hoho, etc).
Anyone has any ideas?
Try working with the sync signal, best guess I really have. I would try a potentiometer.
The thing is, it's synced fine, the picture doesn't roll or anything and it's not shifted down the screen like you'd get if it was outputting closer to 59Hz instead, but overlaying the picture is just a constant shadowed flickering.