Well, I got advice from one of the sales guys at Home Depot last night to go up to Conroe (30 min. drive) and see the guys at Morrison Supply. I suppose this is because they are an A.O. Smith dealer.
I called before driving up there this morning, and was asked to bring the bad part, just in case. I did.
After I was asked the model name (GVRA 40 100), he said, "two years old, huh?" He explained that the GVRA
model was only sold in Texas in 2008, and has a known defective part... the gas valve!
He replaced the gas valve UNDER WARRANTY! I couldn't be happier that the previous part didn't fit, as I saved $58 this way!
Here's the right part:
I got back home, and installed it without a hitch.
I followed the directions (for the most part), filling the tank, purging the air out of the lines, checking all the gas lines, ensuring all the gas connections were sealed, etc.....
I went through the pilot re-light procedure which is old-hat by now, and watched through the pilot window as the piezzo lighter sparked, and sparked, and sparked. No flame. I re-checked the gas supply line, and scratched my head a while. I pulled the directions back out, looking to see if I had switched the white and black wires to the switch. The directions did not specify which wire was supposed to go on which terminal, so I figured I'd swap them and see what happens.
Plunger ---> Spark ---> FLAME!
The water heater is still in its burn cycle, so it isn't dispositive that the problem is fixed, but after hearing what the employee at Morrison Supply told me, I think I've licked it!
Thanks all for the help (and listening to my whines and gripes!)