have you change the gearbox oil? if not could be 40 odd years old :shock: :shock: :shock:
you may need to change the gearbox oil, my bus used to actually move (creep) when in 1st gear with the clutch depressed :shock: i did some research and led to me changing the oil , i remember the gears being quite stiff before hand i change the oil and it all went away happy days