Yep from what you sait sutton the govenor is bad. Its not too much load for your tractor and its HP if you can increase the rpms with the foot throttle when its under a load.
My ym2000 will pick up rpms but just a bit it will still get dragged down some and i can still pick it up with the foot throttle unless its just an overload and in that case the govenor has it wide open anyway and still looseing rpms.
Yours though like i said sounds stuck or not working.