deep well pump won't reach shutoff pressure

1 hp Starite deep well, with packer ejector and foot valve. Filled pipe and pump thru pressure gage. Holds prime. Started with the pressure Regulator completely closed. Pressures to 40lbs. right away but will not reach shutoff pressure of 50lbs. Pressure drops to zero immideiately when power is cut. Please let me know if I can provide any more info. Thanks so much for your time and advice!
Lynn

It sounds like the nozzle in the injector is partially plugged causing the low pressure. Not holding pressure usually means the packer leathers are leaking or a leak in the well casing.

we had the pump rebuilt and they left out a gasket , we carefully cut a gasket and re-assembled the pump could there be an enternal leak in the pump . we have a shut off valve one foot from pressure control valve , so the system should pump up right away , one would think. we had the pipe out of the well. we installed a new foot valve , new leathers, new gasket and plunger internal to the ejector, inspected the venturi and there was no blockage. i am at a loss for words damn it