I was working on our '40 this past year and had the same issue getting the fan blade off when replacing the water pump. I took the pump off and got it in secured in the vise and then sprayed things with penetrating oil good. The I used a small amount of heat with a torch but was careful not to get so hot that I overheated the water pump shaft. A couple of heat and cool cycles along with a couple soakings of penetrating oil it came right off. I still have the old pump and going to have it rebuilt. Good Luck Don