I've been sewing on this machine for 40 years. All I've done is have it cleaned and oiled a few times. I have been watching videos about tension because my newly acquired Bernina Industrial 950 is looping on the bottom of fabric even though the tension is as tight as it can be. One video suggested cleaning tension disc with a pipe cleaner. Another said to always have presser foot raised when threading, which I never paid attention to. I'm gonna try the wrap around bobbin winder tip!