Variable BBC1, BBC2, BBC4 Yesterday signals - sometimes I can pick them up on a Sony TV, sometimes I get "No signal" message on screen. If I unscrew the wall plate everything seems OK, no loose braiding etc. However, if I put a screwdriver onto the screw clamping the signal cable inside the wall box, I can get these channels - is the screwdriver acting as an aerial/boosting the signal. When I remove the screwdriver, the signal is lost. Tried with another TV, in the same socket - same symptoms. Checked/replaced the wall-tv cable too. All other channels apart from those on MUX1 seem ok - signal quality around 60-70%.
