If these are the only channels you are having problems with, it is usually a bad connector somewhere. A bad wire can cause this as well.
First, make sure all of the cables from the outlet to the TV are secure. Then, replace the barrel (F-81) connector on the wallplate itself. These sometimes get worn out a lot in rental homes.
If that did not help, start replacing connectors from the outlet to the junction, then out to the ground block until the problem is fixed.
If this didn't fix it....you actually might have a bad barrel on the back of the TV.
If this is happening on ALL of your TVs, you may have a bad splitter, or it may be an outside problem. GROUND BLOCKS ARE BARRELS TOO.
Try bypassing the groundblock and see if it clears up then. If it does, replace the ground block or the barrel. DO NOT LEAVE THE GROUND BLOCK DISCONNECTED!
bobafett assisted in answering this question.
Note by habu187 : Bad tap plates, loose seizure screws, suck-outs and low signal from actives can be culprits, too.
Note by cableguyrye : Water is a big problem with low band problems, also push on jumpers can cause those problems on an analog picture. U/G areas are notorious for water in drops, black center conducters and such, these i find are more problematic with low band complaints.
Note by joetaxpayer : Too many AC wires crossing near the cable caused 7 to be unwatchable. Replacing the cheap coax line made the problem go away completely.
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