I just took the bobbin case out of my Janome last night to get ready for new project this weekend. In addition to dust I found THE TIP OF A BROKEN NEEDLE!! Imagine what damage that could cause!
Then it took me half an hour to get the bobbin case back in because it is one of those Janome's with the bobbins that does not stay in place. Bah!
But it is clean, clean, clean.