Click. Click. Click. Click. Click. Grr... (Stove igniter repair)

Our house came with an awesome stove. It really is pretty amazing.Except for one thing.The bank of burners on the right, while they lit fine, the igniters took a long time to stop sparking. It's gotten worse over time to the point where yesterday it was sparking for a minute or two to no avail before I gave up.I'm used to having thermopiles used to sense if a flame is present so I pulled the top of the stove off to look for something that looked like it. No luck. The only thing near the burner is the igniter itself.Google to the rescue!It's more complex than I thought originally. And I suppose simpler too.The way these igniters work is by charging up a capacitor and discharging it across the gap to create a spark to light the flame. That part is pretty intuitive. The interesting thing is the sensing! It turns out that a certain part of the flame, the hottest center part of it, is pretty much ionized and after the spark there's another phase where it measures the resistance across the gap. If it's low, it's lit and stop sparking. Otherwise keep sparking away.Now, the troubleshooting tips I read mostly varied between checking that the igniter module is well grounded so it can sense the return current from the sense phase. Also look at the wires to see if they are abraded or anything -- it might be good enough for a spark but not enough to actually conduct a relatively low voltage. Another common culprit is general crud buildup that would insulate the burner.No joy -- everything seemed good.Then I noticed an interesting phenomena -- the igniter module simultaneously hit not just the right bank, but also the center grill portion. On top of that, when the grill lit it immediately stopped sparking.Poor ground can be ruled out!Next I decided on a whim to swap the front and back igniters.Now the back started working. This is the same igniter that didn't light the front burner without continual sparking.The front one worked a bit better as well.But what was different?I noticed that the back burner had the electrode smack between two of the gas ports and the front one wasn't situated like that. Perhaps it wasn't in the sweet spot.Pull out the Leatherman and gently tweak it over a scoch:It still isn't centered, but it's closer.And it works.All the time!(Yes, the first bit is be just barely opening the valve just to show the spark)