I have that error often as well. My favorite needle for quilting is the 90/14. My bad habit is I don't always pull the bobbin thread up to the top as I quilt.That might help. I also find I have to be very particular in getting the bobbin thread through its pathways and making sure it doesn't pop out. Something I also learned here that I now do, is I keep the bottom feet up, rather than lowering them. It works great. You have been here longer than I have so you probably know these things. I just know that the Janome seems fussy when it comes to that darn bobbin.