The old spindle broke. I found one on ebay but it would take a while to get here so thought i'd have a crack at it. Been holding up for abut half a year of light usage with low quality PLA.
Removing the original spindle from its bracket is a bit of a pain with the lock discs. Managed to print the collar tight enough that it can be pressed on with moderate finger force, where it wont fall off easily.
janome-639-bobbin-spindle.stl | 2.4MB | |
janome-639-lock-collar.stl | 47.2KB |