I read somewhere that people used to enjoy reading but the internet is turning us into skimmers who read only the first sentence or two, glance at the middle, and then read the last sentence or two. I'm starting to believe it.
Firing order: check
Possible clue: Engine spins, then starter disengages, while the slight smell of exhaust (not gasoline) is present.
Next step: Attempt starting by towing to eliminate the factor of possibly worn out or gummy starter parts.
I'm not trying to be unpleasant, but really, this has been a very disjointed conversation. I appreciate your help, and when I get the tractor started I'll let you guys know what happened.