Drained what was left of the gas tank and was able to get it out. Now I want to replace the bilge pump and two aerators. The bilge is straight forward but I am not sure about the aerators. How do you go about disconnecting them from their locations? One is through the hull and the other is through the livewell. This is in a 98 21 XD. What is holding them in place, is there a screw or something? It is really hard to see exactly what is going on in there and I don't want to damage the boat in any way.