brake lights

My brake lights have checked out on me on a '76 930, checked the bulbs and fuses, all good, any ideas? Is there a pressure switch on the M/C that might be at fault? Thanks, Tom

Found out what the problem was, turned out to be the brake light switch in the pedal cluster. A bit confusing because the other 911's I've owned have all had power brakes with a brake light pressure switch on the master cylinder. My non-power brakes early 930 has instead a switch at the base of the brake pedal under the floor board that was easy to replace, although I only had to clean the contacts on mine.