1997-2003 F150 and Expedition broken HVAC control knob

I made a video yesterday on how to check heater core flow, and I mentioned checking the knobs to make sure they weren't cracked. This is rare, in my experience. Experience. I've only ever seen this one time 20 years ago. But lo and behold, I must have wished it into happening by talking about it. On a completely different truck, it happened today.