Why is this lower concentric knob stuck?

[dave79]

The top part used a flathead, it unscrewed and came off easily. The bottom part has a hex screw, which unscrewed easily but the knob won't come off. Is there some trick that I'm missing? I've used borderline ridiculous force, there's nothing I can see inside the control cavity, and there is a little tiny circular indentation on the top but I don't think it's possible that it is related...

[Bobster]

Dave,

My concentrics are flat head, top and bottom. Think it could be rounded out?

Best of luck,

Bob

[dave79]

Rounded out? Which part?

[Bobster]

Screw head on the lower concentric screw. I'm thinking it's actually not a hex...

May need to be drilled out if that's the case.

All the best,

Bob

[dave79]

Nah, it's a hex, I unscrewed it.