I just bought a Cub Cadet trimmer from Tractor Supply that was returned because the 1st owner said it didnt run. It runs and it is stong, but it will not idle. I adjusted the idle screw all the way down but no change. I am using 50:1 premix fuel. Is there any other adjustment to make it idle or do I need to return it? The only reason I bought it was because I know the brand should be top quality since so many landscapers use Cub CAdet and they marked the price down so I thought I was getting a good deal.