bfensom, if you have a meter and know how to use it, now is the time. Bulbs can LOOK good but they need to be tested and verified to know for certain. I would check the wiring from the source/battery to the fuse or circuit breaker to the switch to the bulbs. And if you loose voltage at any place, you found your problem. The first quickest test is to turn on the lights and remove the bulb and see if there is voltage there. If so, the bulb is toast and needs replaced. If there is no voltage, time to start tracing when the voltage stops...
