Water Heater pilot won't light

[Octave Doctor]

If the water heater's been on for a few years, the down time may have kludged the thermocouple. And sometimes you get a bad one brand new. I'd buy two, either to have a spare or to avoid a second trip. Yep, one more thing that's not made like they used to be.

Vents can become a problem if somethings been built close by or a tree's grown up close to it. You may need to extend it to get a clear shot.