Have you checked for spark?
Turn the fuel shut off (if equipped) ON?

Primed carb with a couple teaspoons worth of gas?

Sounds like it is time for a long overdue Carburetor cleaning (which should be done at least once every year or 2). I have rescued so many lawn mowers from the side of the road that just needed the Carburetor cleaned out.

I guess I'm about 20 years overdue for my carb cleaning?

A little PM goes a long way. Can you say Stabil?

I totally agree i use stabil in alot of my stuff. My zero turns run off diesel fuel so im not sure if stabil can be used in diesel or not. It has been awhile actually since ive cleaned a carb out on one of my mowers but it is usually the 1st culprit i check when a mower wont start after the fuel filter.