Okay, so for those of you who saw my last thread, I ended up buying the original NES.
It turns out, it plays games that my Yobo won't play, even though they're supposed to be compatible.
It has a new pin connector in it, and everything works great - except I'm getting squiggly lines on the screen.
I checked the video cables, power supply...it's got a new connector so that shouldn't be too dusty...and the games have no such lines on the clone, so I'm going to guess they aren't too dirty either?
Anyone have any idea what's causing this?