I have the 830, bought new 9 years ago. I love the single hole stitch plate and feel it helps me to avoid problems. However, I agree with the fact that this isn't a stitch plate problem. Last time I took mine in, I was told there was a small burr on the bobbin case (nothing I could see). Now that the case has been replaced, it sews like a dream again! Yours probably needs a really good cleaning and check-up. Good luck!
Linda in Missouri