Facing the rear of the machine, it's underneath the bottom of the backhoe seat platform on the right side. In the pic, on the right, about an inch and a half in diameter, with two bolts in the bracket.
Mine drove me nuts too. I put a couple pieces of duct tape over it, quiets it a lot. You can still here it, but just barely. Those same little pieces of duct tape (actually may have been gorilla tape) have been holding on there for years.