[akarma]

I've got a Chinon 50mm that I've been trying to take apart to remove fungus.

I had no trouble removing the inscribed front ring (that says 'auto chinon multi-....), but can't remove the next bit (the bit that has the filter thread on it) or move it in the slightest.
I've removed the two screws from it and tried unscrewing it by hand as well as with callipers in the vacant screw holes. Regardless of how much force I put in it doesn't move.

Does anyone have experience taking this lens apart?
It's possible the front element could be unscrewed first, but that's not normally the case for this kind of assembly and it shouldn't restrict the front bit anyhow.

Any ideas on what I'm doing wrong?