I just tapped in to a cable socket in the wall. This comes off another
cable socket on the other side of the wall that provides signal to that TV,
and that TV works fine. But the TV on this side has "fuzz", or "snow". I
changed the screw-on coax cable, but that didn't help, so I don't think it's
the coax.

How do I test what is wrong with this? I get picture and sound, just fuzz
and snow.

Steve