I have a 4025 (see review), a wonderful tractor that does anything I ask of it. The throttle is beginning to stick. It's not the cables, it's the little arm on the side of the engine, that the cable ends connect to. When you apply the throttle, it pivots. When you release the throttle (foot or steering column), it doesn't QUITE return all the way to the stop, and hangs at about 1200-1400 RPM. I can push it on it very slightly with my finger and it returns all the way. I've tried soaking it with penetrating lubricants, everything I can think of, and it still does it. Any ideas? Am I going to have to remove it?