Hi Paul,another thing to try is to try and stick a small screwdriver ir pick in to try and loosen up the crud in there,is there any water in the block,you can try a small blowgun with compressed air,give it a couple of shots,it might loosen it up enough to get the flow started,you could also knock out a freeze plug and try poking around there,it will be messy when it starts,so be prepared,this is only a bandaid fix,but might save you from removing the motor for now?,if you get it loose you can try some long stiff wire to loosen up some more further in?. HTH Harvey B