HI Richard,My name is ***** ***** I will help with your question. My first thoughts are that maybe the tuner in the tv is faulty, they are normally integrated into the main board so you would need to replace the mainbaord.Have you tried swapping the tv to another room in the house to see if it works fine elsewhere?Do you know how the tvs are connected to the aerial do you have a masthead amplifier or a spiltter?
Hi Richard,I think it would be worth if possible looking at the splitter in the loft. it could be just one of the outputs as failed or maybe has a bad connection. Depending on the type of splitter it is you may find that the cables screw in using F connectors if that is the case it would be easy to change the splitter.It could be the cable from the loft to the tv but I would start with the splitter.The blank spots in the guide are likely to be unrelated and it is just taking a while to update.