I wonder if there’s implications for reduced arcing if any.

@nanofarad that resistor did the trick, this year I finally got around to setting up the little fiberoptic Christmas tree. The LEDs are holding steady with the 100Ohm resistor in series.

No it’s literally that; they’re buying up some stellar brands actually helenoftroy.com

@RussellMcMahon I received a replacement unit from a warranty claim. I plugged it in to a KillAWatt device and measured the following power draws for the whole unit: Low 30.4W, Medium 48.6W, High 67.0W, Turbo 97.3W. There’s a small LED on the unit that you can turn on and off. Doesn’t seem to impact the power draw. Looking at the board again BT1 has a W symbol, BT2 an L, BT3 an M, and BT4 an H. I assume those are for Turbo (whole motor), Low, Medium, and High Fan speeds. The triac that failed was BT3 so medium speed.

When stumbling upon a new component try out a Compare Products feature such as at mouser.com/Compare. The various rows that get rendered and enumerated in the table do well to highlight the key specifications for the parts. If you happen to find an exact match then you've accomplished finding a match and should just order that part. But for close variations you may need to make a judgement call if its close enough. The tricky bit is knowing the characteristics of the device you'll be installing it on and what demands it places on the component. That takes more work to tease out.

@Mattman944 yah Honeywell, which goes by Helen of Troy now, had superb customer service and took my name email and shipping address and sent out a new one. I was still within my 5 year warranty. The unit lasted from 2018 to 2022. When that one's due for a deep cleaning I'll update this post to see if the power supply board is the same and have some additional reference points to share.

@MiNiMe good call on the comma, I just tuned up that sentence. @Hearth I'm not 100% certain but some corroboration could be found in the other two smaller models I own. Both my HPA200 and HPA100 had all 4 triacs oriented facing the same way. Those power supply boards look very similar but do have some differences. One curious thing about them is they use a subtly different triac, the BT 134 600D 1811. Still leaves things a bit inconclusive. I edited the question and offered a full view of the PCB for review. That may help shed some light on the mystery.