In our extension we have a bog standard flat screen ie not sky or virgin etc. Its reasonably modern.....maybe 6/7 years old. A Sony 40". The arial is approx 20+ years old. The TV has suddenly started to give us problems on 2 channels..... 3 & 5. It crackles and is pixelating. I have tried re-tuning several times with no success. My gut feeling is aerial problems (no idea why or how). Any thoughts/advice ???