That's not a bobbin. It is supposed to be a gear with teeth that controls the horizontal movement of the long arm. It was completely wound up with thread. No wonder the machine wasn't tracking properly! We spent a couple of hours on maintenance this morning and did a test run. Everything is rosy once again.
Helen Maslowski is the owner and operator of Cedar House Quilting. She is ably assisted by her most charming partner Geoffrey. (Can you guess who wrote this?)