At ISS Atlantic City the Ink Kitchen hosted “Shop Talks” and one was by Bill Garvin. We had a full house of folks listening to 20 minutes on bobbin tension. Part of the talk was about bobbin cleanliness being essential. His basic message was “don’t be screwing around with the thread tension!”  Instead he said to keep it the same and in order to do that, it is essential that you keep your bobbins clean. Here is a video where he goes over how to clean your bobbin cases.