Welcome to Just Answer and thanks for your question. Janome sewing machines are awesome; I know I love mine. You have done all the proper things that can be done at home. While I know it isn't what you want to hear, your baby needs to go to the sewing machine shop for an adjustment to its workings. Even being off the tiniest fraction can cause the kind of problem you have if there is the slightest tension on the workings as you sew. That is why it happens intermittently instead of all the time. It isn't anything you can do yourself at home. Your machine needs to be set back to factory specifications so you won't have further problems.