My experience is to clean the contacts of the headlightswitch, and bend the springs a bit in form, check if they make contact(!). See http://www.nissan300zx.nl/techniek.lichtschakelaar.htm for dismantling.
Also place a relay, this is why the headlight switch burns, to much current.
Here some pictures how we build in a original Nissan relay in the relaybox (if there is space left) .
If you have a head lamp that flickers or has gone out all together you'll have to determine whether it's the lamp, socket or switch in the steering wheel column. Remove the lamp from the frame and inspect the socket and head light spade terminals for corrosion. If it the socket is corroded best thing to do is to get a replacement from Nissan or the auto parts store. They're only a few bucks. Don't fool around.
If the socket and lamp pins look good check the continuity of the lamp. Using an ohm meter, the three pins should have under 1ohm resistance in any combination. Obviously, if the lamp has no continuity in any one or more combinations it's bad. If you don't have a meter, carefully jumper the lamp to a battery to check the high and low beams. If the Lamp checks out ok, turn the head light switch on including the high beams and check for 12 volts dc at the socket. Two pins should have 12vdc and one will be 0v. If you have an ohm meter check continuity of the 0 volt contact to chassis ground. It should be 0 ohms.
Now, if the lamp is good, there is 12vdc to the socket and good ground continuity, two things remain as the possible cause. The switch in the steering wheel column or the "mechanical" contact between the socket and the lamp. Check the socket first since you are likely to have it out at this point. Commonly the female spade terminals in the socket loosens and makes contact intermittently. Looking into the socket you can see the end of the spade terminal. Also you can see a narrow space along side the terminal. Slip a small screw driver down the space and pry against the connector to close the gap in it. Don't close it all the way. Close it enough to get a good tight grip on the lamps spade terminals. This should restore the normal function of the intermittent head lamp.
If you still don't have 12vdc at the socket the only thing left is the steering column switch. The switch doesn't cost a lot and I recommend replacing it. You can also clean the contacts but this may or may not be a lasting fix. It's your call. You will need a steering wheel puller. A cheap one will do. Remove the horn fuse and then take off the rubber horn cover. Loosen the large steering wheel nut and back it off one or two turns but don't take it off. Set up the puller and start cranking away. The puller will get quite tight before the wheel lets loose. It will let go with a violent bang so be prepared! Once it's loose, take the puller off and remove the nut. Pull the wheel off and grab the washer as you do or it will slip inside the wheel assembly where it may be difficult to retrieve. You should now see the headlight switch. Clean it or replace it. If this doesn't fix it the car's possessed.