I have a 2018 420r and mine is the same especially at low speed and hard lock. Oakmere have looked into this and queried this with Caterham. The reply was, more or les "they all do that" and it will get worse. Before I bought mine I took out a 420r and s, they both did it though not quite as bad as mine. When 'pressing on' there are no clunks or knocks at all. Minty, it does play with your mind a fair bit, but as long as it doesn't fall to bits after the warranty just enjoy!