Newholland 273

My newholland 273 continues to shear fly wheel and knotter bolts. After timing according to the manual, I can turn the baler through a cycle by hand. Then when baling, it will make 3 perfect bales, then shear bolts. The last time I timed it up, it made 1 good bale, then broke a needle. What am I missing? I have followed the manual for everything from adjusting slip clutch, adjusting the needle break and knotter break. I have greased every point. Frustrated as to why I can't get to work properly. Any suggestions are greatly appreciated.

Newholland 273