If it's an E-TEC as your title states, then it's 2 stroke, use 2 stoke oil recommended by the manufacturer
If you have basic electrical experience and own a voltage (multi) meter, check the connections directly behind the switch at the instrument panel. You can check it from the little door in the center console but i prefer to remove the stainless steel plate, much easier to access. If you connect probes to the switch, turn on power and reads voltage (12v), then you know the issue is downstream (burnt bulb, connection issue or corroded wiring along the way. If no voltage on the multimeter, then your problem is either the switch or upstream ( think by the stern, battery, wiring from battery to switch. Wires run inside a tube conduit from stern to the center console and again from console to bow nav lights.
