HVAC Dials Replaceable?

[06YarisRS]

Thanks very much, komichal. I hope that the peg has just slipped out as that would be an easy fix. The funny thing is, is that when I turned the dial, there was no more than the typical resistance which is almost nil. I did feel a slight snap but I suppose it could have just slipped out of the retaining hole. The video I linked was good, but didn't really show or demonstrate what causes it to pop out of its hole. And, I do hope that the flapper door is not my issue. I'm also hoping that I didn't actually damage my HVAC unit when I was creating the dent in my firewall for turbo clearance.