Since it does seem to work in one spot, I would wonder if that is at the beginning of your sewing/quilting session. If it does sew better at the beginning, finish that section, then when you want to move to another section turn your machine off and leave the room for a few moments to rest, stretch, de-stress, and have a drink of water! Then when you are a bit more relaxed, remove and re-thread the top and remove and reinsert your bobbin, as if starting fresh again. Some machines are very fussy and need some TLC. I have also found that using the same thread top and bottom is crucial (different colors are okay)! My mom has a Janome Quilter's Companion that seems to be a little needy, as well!