Have you changed needles and completely rethreaded the the machine, including taking the bobbin out and reinserting it? My Janome was having farkles the other day and nothing I did made it work right. I decided the clean it, and when I did, I discovered that I had the bobbin case in wrong. I was about to decide the devil was tormenting me because I was making a table cover for the church. LOL! Good luck!