If you want your machine to stay happy, this is the most important maintenance procedure!
Clean and Oil the Hook and Race:
*(This procedure should be done after every 6-8 hours of sewing)*
Bernina Oscillating Hook
(for example: Aurora models 130 thru 170 & 220 thru 630)
Bernina Rotary Hook
(for example: Artista models 180 & 200, 640 & 730)