Apologies for the late response.  The video used to slowly scramble out.  This could take up to 10mins.  You start seeing lines across the video, and then becomes a little shaky and scrambles, and then eventually you see No Video.  But now it goes from video to complete black in a couple of seconds.  Some hours later it then comes back to life again.  This only happens during the day.  During the night it's fine.  Images attached.