Sound has not worked via HDMI since the box was installed. Sound on TV AV1 Scart input is fine but picture quality is very poor. Picture is good via HDMI input. Sound and picture from LG DVD player is fine via HDMI. Have tried 2 further high speed HDMI cables between the box and TV. Have tried all HDMI inputs, including ARC. Mains reset and standby button reset tried on the box. Maintenance mode reset tried (not delete recordings). Have also tried all settings on the box and TV.