Home rebuilt 1920 has poor accel shot

After rebuilding my 1920 I've noticed that immediately off idle when pressing the pedal The car slightly hesitates.

After checking the carb for vacuum leaks I noticed that when I hit the accelerator the pump shot is kind of weak. Weaker than before I rebuilt it. I didn't pull the lead plugs from the metering block just blew it out with carb cleaner and compressed air.

What could cause this issue ?

My thoughts:

Bad diaphragm (new)
Incorrect float level
Issue with checkball? I don't know how it functions
Clogged shot port ?