John Deer 459 conventional baler

Hi everyone, new to this forum but hoping you can help. I write this in despair! My 3 year 459 baler frays the string after the knot, so when you pick the bale up the string breaks. Can anyone point me in the right direction as to what's causing it. It does t always happen but the it has a spell of doing it all the time. Thanks!

John Deer 459 conventional baler