6 switch 6 switch 2600 fuzzy screen. What components do I need to replace?

[Idontunderstand]

Hi everyone. For the last 20years I have had a keen interest in the the old 2600. I've previously had to part with a few that didn't work. I have now got a couple more that want to work but need a little help and I thought it's about time I learnt how to fix them. Here a the videos of the screen. Ones very fuzzy and the other just shows the space invaders image 

What bits do I need to replace?

 

 

Any pointers would be appreciated.

[alex_79]

It seems that the TV is on the wrong channel. Are you sure that you tuned it correctly?

 

[Idontunderstand]

Hi yes. I tuned it in. My other 6 switch works fine but these two don't want to get any closer than as you can see.