They are inertia belts, they have a ball bearing (or similar) on a plate, once the belt reel moves or is off its centre then the ball moves to prevent the belt from slackening off, this works in conjunction with the pre tensioner in the seat belt buckle in the event of an accident to hold you securely in your seat.
Anyway enough waffling on, basically once the belt is removed it's difficult to get it in the correct position to unwind the belt, bolt it back in and it'll work as it should
They are inertia belts, they have a ball bearing (or similar) on a plate, once the belt reel moves or is off its centre then the ball moves to prevent the belt from slackening off, this works in conjunction with the pre tensioner in the seat belt buckle in the event of an accident to hold you securely in your seat.
Anyway enough waffling on, basically once the belt is removed it's difficult to get it in the correct position to unwind the belt, bolt it back in and it'll work as it should