926 moco chatter

Used my mower for the first time the other day as I was making turns (not that sharp) hearing chatter. This is the first time I've mowed with the new tractor, never had this issue with my old tractor 5520 the new one 5100m seems to be the same drawbar height so anyone have any experience with this. It was greased prior to going out. Thanks

926 moco chatter