I try to have my machines cleaned and checked by a dealer at least once a year. That way if something is going wrong hopefully it can be caught. Besides they can get into places I can't. I clean my bobbin area every time I change bobbins. I encourage my students to clean their machines often. I even ask when their machines have been cleaned lately. I tell them they wouldn't leave their babies in dirty diapers, why the machine. :lol: