I am doing piecing..making some 9-patch blocks. I have a small Brother machine. I've had it for years. It is a real workhorse. The bobbin is the type that you put into a case before inserting it into the machine. The owner's manual just says to adjust the tension but that's not working. The bobbin is in correctly...same way I've always put it in and acc. to the manual, it's in the correct way. I am at my wit's end, trying to figure out what is happening.