Intellivision top 25% of screen flickers

[Intellivision top 25% of screen flickers]

I am using a coaxial cable. I tried replacing that with the same results. I haven't yet replaced the male to female adapter since I only have one. I might try the rf modulator, though I have never soldered anything before.

[Intellivision top 25% of screen flickers]

Games play perfect. I will try it on another TV. Is replacing the rf modulator an easy fix?

[Intellivision top 25% of screen flickers]

Any help would be greatly appreciated. My Intellivision flickers with every game I have loaded. I took it apart looking for anything that might be loose and didn't find anything. I am not a hardware expert so I didn't monkey too much with the insides. I tried cleaning the cartridge slot with QD Contact Cleaner but that did nothing. Also used compressed air to give an overall cleaning.

Thanks!