As I feared, mine stopped working today. I pulled off the ballast and checked continuity in all the wires from the plug to the ballast and then from the ballast to the ignitor plug. I have the common problem of cracking insulation on the wires, but I had proper continuity on all wires. I cleaned the contacts on the ignitor/bulb face. I also noticed the little ground tab that contacts the housing of the plug going into the ignitor looked a bit flattened, so I pried it up a bit with a small screwdriver.
I put it back in and it worked. In fact, it worked better than yesterday, as it comes on immediately. Yesterday when I finally got it to work, it had a 10ish second delay before it would come on.
I'm still leaving the bumper off until I'm confident I have it working reliably.
AM.