I think that it is probably your machine. I have had a love/hate relationship with my Janome 6500 for those very same reasons. It always balks and jumps or jams at seam junctions and veers off the seam line at the end. It also likes to munch fabric at the beginning of your stitching. Taking it to my dealer numerous times has never helped, the problem was never corrected and all the dealer ever told me was that it was "operator error". I will never buy another Janome or do business with that dealership again. I am now considering a Juki Exceed 600 or the TL 2010Q.