I want to thank you guys for the information in this thread.
Last Sunday I got back from a week's vacation, and was welcomed by...NO HOT WATER!!! Oh well, I'm one of the lucky ones, as my Whirlpool FlameLock water heater worked for two years, eight months before the thermocouple threw in the towel.
I ended up shelling out $24 for overnight delivery of the "Manifold Door Switch Kit" (part number 6910813); however, I did NOT get the wraparound filters to go around the bottom of the unit. I agree with others that it's kind of stingy to charge shipping for this, but then again, the optimist in me is happy that a great deal of my water heater is now brand spankin' new.
I'm a reasonably handy do-it-yourselfer, and ended up getting the kit installed in a little over 30 minutes, including the time it took to clean the air grate. However, it bears mentioning that I had taken out the old unit the day before to troubleshoot, so I had an idea of how things came out, and went back in. Fortunately, I'm handy and fairly limber...I couldn't imagine what an elderly or otherwise less-than-fit person would have done.
Bottom line is that I'm glad to have this fix in place, but I wonder how long things will STAY fixed. Guess I'll end up changing this tank out to a Bradford White if it happens again.
Thanks again for the posts guys...it really made my task MUCH easier, and I'm back to taking HOT showers!