This is typical of a poor connection, not a failed lamp. However, if you were to replace the lamp you might think "I fixed it!" In that case, the poor connection was probably that between the lamp and the three-pin socket on the outer of the quad array.

Just behind the lamps is another spot which collects water and becomes a high-resistance bump in the path. There's a connector. The pics below show the problem and the repair in a worm's eye view, but if you follow the wires you find it. The blue wires are the low-beam wires.

And the ground. For the right one, I think the ground shares a screw which mounts the windshield washer bottle, if I recall.

Finally, the bulb-out sensor is the last place the right and left circuits are separate. Those of the '82 era are not as troublesome as the later units with three stacked circuit boards, but have been reported to develop poor solder joints.




--
Art Benstein near Baltimore

"Airspeed, altitude and brains. Two out of three are needed to successfully complete the flight."