Pre-wound Bobbins "Sticking"
I'm wondering if it's just me or if others have had this problem. Some pre-wound M class bobbins have "sticky" areas, where the thread doesn't come off the bobbin easily. For example, if you put the bobbin in your hand and pull up on the end of the thread, the bobbin comes with it. I've had the issue with both Superior pre-wound bobbins and Glide Magna Glide. There are usually 1 or 2 bobbins in a package that I end up having to throw away because of the issue.
I did call Superior and they said they had never heard of the issue before, but replaced a box of bobbins for me anyway. I know that many of the pre-wound bobbins are overwound, and I'll take several yards off and still have the sticky problem, as if they were wound incorrectly.