I have a NSF4B Nisan 4hp 4 stroke 2005. The warning light is flashing or is on continually. I replaced the oil pressure switch and that didn't correct the problem. I took the oil pressure switch out and installed a pressure gage. Started motor and gage needle flickers between 0 and 3 lbs. I just bought the motor so I don't know it's history. I can tell it hasn't been used that much. I do know it hasn't been run since 2007. Any and all suggestions welcome.