Hey peeps, I can't for the life of me get this oil leak sorted!!

After having oil dripping on to the cat for week, I decided to changed the rocker cover and cam chain tensioner gaskets as I have read that this is normally the main cause. However!! This leak still remains as is really doing my nut as I want to sell the thing and cannot do so with this leak.

Can someone please help me and suggest what info next.

Thanks guys.