Rough Running Victa 35 series (New)?

I have a brand new Victa 35 series mower with a Briggs and Straton engine. It has never missed a beat until a week ago it started running rough. I removed the air filter and found behind the main carb linkage there is a little linkage with two springs coming off it one large one small and it just keeps moving forwards and backwards which I assume is causing the problem. I have spoken to three other people who purchased the same mower around the same time and they have all said that they are having the same problem. Have been told that it needs to be taken in and serviced but it is brand new.