Gen I Prius HVAC knob removal

Apologies if this is in the wrong place.

My partner has a 2001 Prius that has several bulbs burned out behind the climate control knobs and other buttons in that area. I was able to disassemble the panel partially but it looks like I have the remove the three knobs from the HVAC controls to get it completely off and access the bulbs. Is there a secret clip or screw somewhere? I tried tugging on the knobs and they wouldn't budge.

I've been working on cars for years but mostly European and rarely anything this new. The dash is a bit of a puzzle with no exposed fasteners.