9. What will be the reason if roving bobbins are not hanging straight on the bobbin holders?

The bore of the empty bobbins has a boss extended inside with a chamfer at the end, where in the holding levers of the bobbin holders are seated. If this would have been damaged the levers may not get seated properly and parallely. And also, in some make of bobbins the ribs provided for boss support will be projecting above the boss, and this will disturb the levers from parallel seating. If so, the bobbin should be immediately changed.

The international concept for the bobbin design if of no ribs projection above the boss. And this will have the levers seated parallely.