I'm not sure about a 65, but in as much as they look a lot like a MF50, which I have, here is a thought. When I bought mine, it would not hold the throttle setting (mine is a diesel). I would bring it up to speed and it would creep back down. What I found, with some helpful advise here, is that the throttle lever is held in place with a spring loaded friction disk made of cork. It is under the dash. My cork disk was missing completly and therefore no friction and the throttle was free to move on it's own. The Massey dealer had one of these for a couple of $$ and it is like new now.