Do you have an ultrasonic cleaner? It will usually vibrate off. If you dont have one try holding something that vibrates with a high frequency (any electric motor eg elec toothbrush) next to the case and see if it comes loose.
Sometimes a vintage watch will have no room to access the spring bar with a knife edge. And you have no choice but to pry the band off the watch. 99% of the time this is done without bad things happening. But you run the risk off the pin breaking off flush in the case lug hole and it is almost impossible to get out. Does anyone have a neat trick to remove it from the case lug hole?