If anyone's still reading this ancient thread, I just fixed my own radio knobs using the info posted here. Thank you all!
I can confirm that the circuit board mounting screws are 1/8" hex heads, for which I had to buy a driver on Amazon:
https://www.amazon.com/dp/B000O5EFX4?ps ... ct_details
It fit perfectly, though it was tougher than I expected to get them all out -- that driver has a narrow handle to avoid over-torquing tiny electronic components, and these are self-tapping screws driven straight into plastic.
Also, those 10mm bolts holding the radio assembly in are really easy to drop, and at least one of them will disappear behind your dash. I didn't lose the bolt, but I did lose a small magnetic pick-up bit (used to magnetize the driver) which I'm hoping will harmlessly attach itself to something back there.