Okay, here's the problem:

I have a cable box that has a few problems. Worst, it introduces a horizontal line into the picture. The horizontal line is colored and it travels slowly from the bottom of the screen to the top. You can see the line pulsate whenever the refrigerator cycles, etc., although some days it is not present at all. I am pretty sure it is a problem with the grounding inside the box -- which cannot be easily opened -- and it is introducing the 60 hz AC interference into the picture. In other words, it's not from external interference, it's a short.

I'd like to remove that interference, but I'm not sure how.

Here's what I have narrowed my options down to:

• Buy a signal attenuator. I don't think this will work for this problem, but would be the cheapest solution.
• Buy an antenna amplifier. I know, I really don't need to be amplifying this signal, but my theory is that the amplifier will selectively boost the good signal and filter the interference. Am I kidding myself?
• Buy some type of filter. I have no idea what will work. Any suggestions?
• Buy some type of video stabilizer that would strip the interference, but it would have to have an RF connection, not RCA-type connectors.
• Build something myself. Would adding resistors simply drop the signal below useable strength, or could I effectively weaken the electrical interference this way?