Bad NES Gyruss cart

[RMila75]

I have a NES Gyruss cart that plays OK except for a pattern of white "dots" spaced evenly all over the screen. It never used to do that, but one day I started up the game and there were the dots on the screen. No other games do it. The game is very clean and was never abused since I've had it. Could it be static electricity damage? I once heard someone mention that but I don't know what symptoms that would cause.