All right, never mind everyone. Once I broke a chunk of the sludge off the wall, it's all been breaking loose now. Now when I stick a flashlight in the tank I can see mostly metal. and the nuts keep coming out when I dump the water. Before they would just get buried in the mud and stay in there. I think spraying the hose into the bottom opened up a spot and now fluid can get under the sludge layer and is helping. Now I just need to get a new petcock and move on to the next thing. Thanks for the help on this, as usual.