Stocks from IBD's Sector Leaders screen mostly lost ground Thursday, as the main indexes endured mild losses. A couple of Sector Leaders drew strong turnover as they made big down moves: 3D Systems (DDD) and SodaStream International (SODA). 3D Systems tumbled 2.55, or more than 4%, to 57.85. The maker of 3D printers touched its 10-week moving average and came close to hitting its 50-day moving average. 3D is finding support at its 50-day and