Water Heater Problem

I want to finish this topic off with what seems to have worked. I cleaned the orifice and made sure the gas supply tube was clear. WH still did not work (still had weak, yellow flame). Then I got a brush that made it through the burner tube and ran the WH gas (with sparker disconnected and connection covered with electric tape) VERY briefly without orifice installed. (I can't really recommend this because it could be dangerous if gas was somehow ignited.) Now WH is working again. I was reluctant to do two things at once because I can't tell if burner tube was blocked, but WH was turned on (to gas setting) and working when problem started. My guess is that the gas switch was not opening all the way, and reducing back pressure blew something out that allows normal operation (at least for now).

JRMunn