quiltedsunshine

There are a couple symbols that come up on your Bernina.

One just comes on when you do so many stitches. To get rid of that one, you need to take it to the shop and have the tech re-set the service panel.

Another symbol indicates that the thread isn't bouncing in the check spring correctly, or "upper thread break." To fix that, remove the cap on the end of the machine and put the check spring back into position. That happens sometimes when the machine is going really fast, then stops on a dime.

I don't know of a "clean bobbin case" symbol, and I'm a Bernina tech. What does it look like?

Edited to add: There's also a low bobbin sensor on the B640, which the tech can turn off in the service panel. It can be particularly persnickedy sometimes.

Remember... if you sew every day, your machine needs to be serviced every year. But never go more than 3 years without a service. It may just be time for a service.