[Sr.No.] 6 [Possible Cause] Pump check valve jammed by drop pipe [Corrective Action] Unscrew the drop pipe and cut off a portion of threads. [Check] 
When pump is pulled after completing step 5, examine connection of drop pipe to pump outlet. If threaded section of drop pipe has been screwed in too far, it may be jamming the pump's check valve in the closed position.