Shaft Key ? Is it on the pump shaft and all intact? If it's not the motor won't turn it. I'm guessing no it's not. But the good thing is turning it by hand a Fluid is moving. That's a good indication the pumps good.
I just ordered a 24" 1/2" hose and that thread past. I will wait till later to see if there is any more input on what to check before I put the pump back in
Wow! Got Ya! So that is the Female Hex. in the motor in the pic. above. Then you should be good. As in turning the pump. Back to making sure Fluid is getting to the pump. and nothings coming out Bad Pump!! IMO...