Thanks everyone.
Removing hose from carb and there is no fuel flowing out of the carb.
When I do the blow test no air gets in.
The lower hex train plug – you mean part 34 in the carburetor parts diagram here
https://outboard-boat-motor-repair.com/Evinrude%203%20HP%20Lightwin%20Outboard%20Boat%20Motor/Evinrude%20Johnson%203%20HP%201952-1954%20Parts%20Manual.htm
Upon close inspection it appears that this has been snapped off at some point!
