Humax has been in standby for the last 12 hours. Woke it up to watch Midlands Today on BBC 1 and the picture was minimised in the top left corner of the screen, with a coloured hue. Video passes through a Marantz receiver so power cycled that with no change. Changed the TV source to its internal tuner as an interim measure while we finished our tea. Later switched back to Humax picture (still the same), changed channel +1 and BBC 2 was okay, so changed back and BBC 1 also fine.
Is there anything I should check?