Clio MOT failure side light / hazard light problem

Hi Guys looking for some urgent help to cure a problem which caused car to fail MOT today. The rear side lights work ok. But when the hazard lights / rear side lights are on together the rear side lights flicker, they dont go out completely, hence the car failed. Have tried replacing the side light bulbs but no difference the rear side lights still flicker. Have checked the the lights units and there doesnt appear to be any build up / corrison on the terminals, also the connections seems ok to. would this be an earth problem ? if so where else could I check for a cure.



Thanks for viewing.