Going to do this next. Now have to locate an air compressor.I would pull the fuel like going to the water seperator and see if fuel runs out or just dribbles. If it just dribbles, use some compressed air and blow air back in the fuel tank and see if it does run out then. I had this same problem when I first got my tractor. Make sure you have something that you can clamp off the fuel hose while you are doing this and a good sized can to drain the fuel into.
If the water separator bowl is off and the fuel cock open shouldn't the diesel be flowing out? Or is disconnecting the hose to the water separator the only way to tell if it is blocked?
Update to previous info: Fuel filter was replaced, fuel bled, battery charged
And the seat switch issue was encountered last year. It's firmly tied down now.