24 volt 1979 BJ40 with Aussie 3B engine. Had no oil pressure reading when purchased. Grounded the wire leading to the sensor to verify that the gauge was good. It went to max as it should. Replaced the sensor with a Sankei KG-813. Still no pressure reading. Performed the sensor test in the FSM. With engine off test light was off. With engine on at idle test light glowed faintly but never did flash. Did I get a faulty sender or is it the wrong one? The old sensor was marked 12v while the replacement was 24 v. If I recall correctly the old sensor also failed the FSM test protocol. What to do?