I have a BL....and recently was doing a blanket stitch, and suddenly it went crazy...took it in after trying all I could do....and it went crazier for the dealer...she had to call someone via phone and was told some secret..she went on the screen into the brain of the computer...punched some formula...started it....it stitched some strange circle by itself...then she picked a stitch on screen and perfect!!!!!! Had something to do with internal settings that only the techies can fix!!!!!! Maybe yours did the same...