I've had a Bernina 830 that is 43 years young. I take it in occassionally to have it cleaned and oiled. The problem you have may be that the bobbin thread is not in correctly. My machine will us any type of thread. It is a very accurate machine. Thus, if anything is off it will mess up your stitching. It is a top line machine. The suggestion to take it to a dealer is correct so you know how to use the various settings. Good luck.