Before taking your machine in though you should give it a good cleaning, change the needle, and rethread just to make sure its not just something simple like lint and fabric caught in the feed dogs causing problems. For brothers it can also be putting the bobbin case in wrong that causes jaming, the needle, plate bobbin plate, and bobbin case all have to be put back together in a specific order. if you don't your bobbin case won't spin right and will become jammed everytime. I wasted an hour in a FMQ class because I put it back together without looking at my manual and it kep jamming, so i took it apart again, look at my manual and followed their instruction and sewed like a dream after that.