I have a Janome 7330 Magnolia & just today it stopped sewing correctly. I first noticed something strange when I tried to bring up the bobbin thread. It wouldn't bring up the thread on the first time but would on the second time. I tried re-threading the bobbin & also the top thread several times. I took off my bobbin cover & bobbin case & cleaned everything really well & that did not help. Then I replaced my needle & everything works like a charm. Must have been a burr or bent needle or something like that. Maybe try replacing your needle.