For many years, I've purchased bobbin cases where I wouldn't need to adjust the tension at all. They were just perfect. But the last year or so, I have been getting cases from different vendors that have a certain sticky glaze on them that is very hard to keep a constant decent tension on them. On previous cases from a few years back, they had a little bit of an oil on them that made them smooth, not sticky. Where do people get decent cases nowadays?