Bernina 830 being a pain
They are picky machines. I've had mine about 1 1/2 years. Its biggest problem is the automatic threader stops working. Have you tried contacting Bernina directly, via email or through their website. And, it wouldn't hurt to find another dealer either if yours isn't taking care of the problems. If you can find one, I reccommend taking the Mastery class for the 830. There's so much to this machine & the class covers most of it. I use Bottom Line thread for the bobbin & either Gutterman, King Tut, or serger thread in the top. My dealer also suggested using canned air to blow from the back of the bobbin case towards the front to blow out lint in hard to see places. I also oil it about every 2 bobbins or when it begins to rattle while sewing. Best of luck.
Cathy S/Willowwind