I hear what you're saying Bert but I don't know enough to comment further. To me a bobbin is a bobbin is a bobbin. If they're wobbling I would have thought that would be a problem with the shaft rather than the bobbin. I can see where there might be a problem if the shaft is opened so much that it's only gripping on the end and I can see where you guys might have a beef if you've paid big bucks for new macines but on my old Durkop I would just open up the split, put something in the back end of the split and close the front with some pliers to get it back to parallel if that makes sense.