I'm going out on a major limb here so I hope you'll take my comments in the spirit in which they are offered.
I read back through all your threads to be sure I understand where you are at this point. I know you listed, in this thread, what you've done so far, but that still does not sort it out in my simple brain. Here are my questions:
1. You added a new fuel line without a filter. Are you sure the fuel line is the correct size per the manual?
2. After adding the new fuel line did you fill the tank adequately to check the fuel flow in both the On and Reserve positions? I don't see where you were ever able to get good flow in "On". Maybe you did and did not post about it.
3. You say there is no problem with the fuel flow from the tank to the carb but you are basing this only on the fact that the plug is wet and, I think, you said you had fuel in the bowl of the carb on one occasion. This only proves fuel got to the carb at some point but doesn't mean you have a good constant flow.
Also, you said you thought fuel flow was good because you blew air through the petcock. Sorry, but air from the outside into the tank may just push any debris back into the tank and it will settle again against the petcock filter. AND, that petcock filter just slides on and you may have knocked it off when you flew air through it.
4. Are you positive your fuel selection knob is in "ON' and not Reserve or somewhere in between. My On position is about 1/2 inch past the On position. You mentioned several times that you did not have much fuel in the tank. Are you cheaping out because you don't want to waste fuel? LOL. Fill that puppy up at least 1/3 of a tank. You'd be amazed how much gas needs to be in the tank to crank it.
4. As @shadetree
mentioned, be sure you gas cap is sealing and that the vent tube is not stopped up.
I'll throw in #5 for the entertainment value. Part of my job here is to make you laugh.
5. Are you sure, really sure, the kill switch is off. Flip that switch back and fourth a few times and be sure it comes to rest in the centered position. It's fooled me more than once.
Sorry for asking all these things but I can't get past the fuel delivery issue. I hate to see you trying all these things when you may not need to.