Got a b riggs 25hp, I have the engine out and need to replace the crankcase gasket. I cannot get the crankshaft pulley off to save my life. I rented a heavy duty 3 arm puller and it just bent the pulley it was that stuck, i've sprayed it, used heat, I don't know what else to do it's rusted on. Does anyone have any advice I need to get this thing going asap-thanks