I'm looking for some technical help with a colecovision console. I'm getting some sort of minor video scrolling interference since I've owned it the past year. I've ruled out the Power Switch (even bypassed it to double check), and it's not the power supply since it works great on another unit I have. Video below:

(really noticable on the words popeye and olive near the top)

Some notes:
I A/V modded the console, and the interference shows up AV out and via coaxial
Does not show up via the Atari 2600 Expansion Module
I've reflowed most of the solder joints related to power and grounds
I've visually checked for broken solder joints and find none
It is present to some degree on every game I have

I have some small electronics experience, but not much. I'm am an amateur, but not afraid to dive in and learn more.