Janome Bobbin Case (858570009)Janome Bobbin Case (858570009). Whether you are replacing a worn bobbin case troubleshooting tension issues or keeping a spare on hand for different thread types using a genuine Janome bobbin holder helps protect your machine's performance and longevity. Replacing the bobbin case is often a simple and cost effective way to restore stitch quality. Over time bobbin cases can become damaged by needle strikes lint build up or general wear. Signs you may