I have a 1965 35hp Mercury outboard and need to replace the impeller. The problem is that i cant get the lower unit to come off. I have remove all of the bolts holding it in place as when as the shift arms up top. I have gotten it to fall about 3/4 of an inch and dont know how to get it the rest of the way off because it seems to be stuck. Is there something else that needs to be disconnected? Or a way of forcing it off? Thank You