New Holland D1010 Large Square Baler. Safety Nut breaking

I am using a New Holland D1010 Large Square Baler with a 100HP Fiat Tractor for baling Rhodes Grass Hay.

The safety nut next to the "weight" where the PTO shaft coming from the tractor end, keeps on breaking. Sometimes 3-5 times every 2-3 Acres. We are currently using it at level 50 (Bale compressing level) and making 7'2" bales.

Can someone please point out the reasons why this happens and any precautions we could take to avoid this. Furthermore, what is the average baling capacity of this baler per day.(12 hour working shifts) Thank you

New Holland D1010 Large Square Baler. Safety Nut breaking