How many of you have boxes of bits that have been passed on from friends and family? Do the boxes include an assortment of bobbins? They often do. I’m sorry to disappoint you but chances are, you can’t use the bobbins in your machine.
You see, all bobbins are not equal, they come in different shapes and sizes with the differences often are very subtle so that you probably can’t tell just by looking at them. For example, I have a Brother machine which I use at home and the Janome machines use for teaching. They both have plastic bobbins that look very similar but they are not the same and cause problems if the wrong one is used. I have to be very careful about keeping them separate and thankfully, there is a very slight blue tint on the brother bobbins and a very slight yellow tint on the Janome bobbins so I can tell the difference.
So, if you are having problems with your machine and you have checked everything else, make sure the bobbin you are using is the right bobbin for your machine.