$900 and 16 bulbs later, we're good until next year this time
9 of the bulbs will remain off from late May thru early Oct, which those are outdoors during that time.
Solar meter 6.5 was a game changer for me. You can not only check the viability of old bulbs but also check new bulbs. I have found several bulbs new out of the box that didn't produce any uvb.