My investigative instincts would point my suspicions directly at the largest whitetail buck living in the area. All the while you were stooping over that drawbar to pick it up, and during your walk back to the tractor in the barn, there were probably dozens of six-ten pointers prancing around behind you, laughing, and laughing.
I'd reinstall that drawbar and lay in wait to see if the critters sneak back into your barn to sabotage your tractor again.
Just can't trust venison these days. /w3tcompact/icons/grin.gif