Hi There... Did you ever get this problem solved?? If so what was it?
I'm in the exact same situation with the exact same mower. I got it from a neighbor. First problem was the gas tank leaked. I replaced the tank and it turns over and starts for about 1 second then dies. I haven't cleaned the carb and all ths stuff that you did yet. If I have to go through that I'll probably just return the mower. Spark plug does look wet and black. Cleaned it once but didn't do much. Made sure I used the original vented gas cap, even tried starting it without the cap on. I may have really flooded the carb by priming it a lot. I thought since the gas lines were drained I needed to get the gas flowing.
Anyways, just curious if there was a silver bullet that finally solved the problem.
Thanks
scott