I have a question, is it possible the reason the needle is hitting the plate is because a straight stitch plate is on the machine? I use a straight stitch plate on my Bernina when I'm piecing. I have to remember to change plates when I switch to decorative stitches. If I don't, I will break a needle and I may hurt my machine. Just a thought, hope you figure it out. I know how expensive vet care is. But at least your dog is getting better.