Clunky is a bit subjective but might mean you need some grease on the engine or gearbox levers depending on whether it is “clunky” with the button in or not. Stiff might be the cable is sticking which is more difficult I think. It might be worth someone moves it while you look at the engine linkages to see if one sticks and then moves – with the engine not running!
The membership association for owners of Dufour Yachts