Well, the water heater is working again. It was honestly a real pain in the butt to replace the gas valve mechanism. All the gas pipes had to be removed piece by piece, because they were in the way when unscrewing the valve itself. Also, the sediment is too thick, and the drain valve won’t drain out the water. So I had to just quickly swap the old gas valve and the new one while the water, “GLUB GLUB GLUB’d” out of the side of the tank.
Once reassembled, the unit fired right up, and appears to be working well. I did order a replacement drain valve, and when it arrives I’ll do my best to drain and clean out the water heater tank.
Anyway, I’m pretty sore from hunkering down and wrenching apart gas lines with big pipe wrenches. The basement isn’t exactly a comfy place to work in our house, and I’m not exactly a spring chicken anymore. But I’m grateful that I was able to repair the hot water tank, and that there weren’t any major hiccups along the way!