Back to the needle hitting the bobbin case. I was told by my Bernina dealer that when you put the bobbin case in you should hear a click. I have owned 4 Bernina's some are a little toucher than others about clicking into place.
My daughter purchased the 440QE about 1 yr ago. She had to take it back to the dealer to have them adjust the a piece in the shuttle area that holds the bobbin case, because it would not click in place and stay there. It sounds like maybe that is what your is doing. Hers worked after that.
Hope you get some help with this.