I heard a rapairman talk about this. He happened to work on Berninas. I believe the advice goes to all the machine brands. He said don't settle for the generic bobbins as they are not always accurate. Said even a slight difference can work against you. He said to take the generic bobbin and let it roll over a smooth surface. See if it rolls straight.
Specific bobbins are tooled for the mechanism of the specific machine. Generics are "one size fits all".
I know they are less expensive than the brand bobbins but to me not worth the frustration they may cause. Better to have fewer and less worries.