Removing a aperture ring plates

:confused: I thought I'd give it a go trying to make new aperture leaves for
a brass lens and trying to get the aperture rings out is turning out
to be quite frustrating. The aperture mechanism rings seems to be held in
by another tube, the left picture, it looks thick enough that it might have threads
but then it could be press fit.

I've PB blasted it, applied lacquer thinner, used and expanding rubber drum
to try to twist it out / pull out the inner tube, spot heated it, froze it, froze the inside tube and heated the outside,
baked it and the assembly still doesn't seem to want to come out.

Any thoughts on how to disassemble this ?

Attachment 97214 Attachment 97215