My big walk-behind mower has a Kawasaki FH451V 15 hp twin.

I left gas in my big mower for two years (I know better). Decided to run it recently. I drained the old gas and have fresh gas now. It will not continue to run unless I keep the choke half closed.

Seeking help with most likely problem; my ideas include:

Clogged Fuel filter

Gas pump (I think that's what the plastic tiny tuna can after the fuel filter is).

Clogged needle valve (I have no info on the mixture control, whether it is fixed or adjustable, and I have not yet removed the shroud to inspect).

Leaking fuel line.

Will appreciate any guidance on what to check first, and whether I've missed something.