Hi Steve,
When the light worked, did all bulbs illuminate, lets start with a baseline of everything was functional.
When I upgraded to Litronic headlights from oem halogens, my light switch started to act up as you described. It would sometimes come on if I tap the switch or click it back and forth but mainly no light. So I did some research and it turned out that the Porsche light switch goes bad more than you think. I bought a new switch unit and installed it. Put the Litronics back and it works every time. You can try getting a new switch module (pictured in the red round thing) a new one should take care of the problem.
best
