I was also wondering if the pilot light pipe and orfice could be plugged somehow. Any way to take that piece off the gas control valve assembly and check and clean it? Not sure how this is put together so I'm guessing. I believe there is another pressure regulator in the heater and that could be messed up. I guess I'd start taking the gas lines apart wherever possible and try and isolate where the flow stops. Never had to dig into one. Anyone else with ideas?
Al