Information concerning malfunctions and repairs should also be recorded in the station log. A trained eye can usually spot when one light in an incandescent dual-beacon fixture is out. Binoculars can be very useful for checking this, as well as looking for broken or open fixtures. Most incandescent alarm relays will dropout when only one lamp is burning. Mechanical flashers should be periodically lubed, and their contacts burnished when necessary.
Some mechanical flashers get very slow when cold weather causes the grease to harden.
Most modern designs use a solid state flasher, which will not wear out mechanically, but may require replacement after a direct lightning hit. Strobe systems should be checked to ensure that the lights change from day to night mode. Although the public is getting used to strobes you will hear complaints if your system stays in day mode during the night. On either a strobe or red light system, you should make sure that the photocell eye is clean and is facing the north sky. On a hot AM tower you will likely have a lighting transformer to isolate the tower from the power lines.