Rotate the Focus Ring to the closest position.
Once the Rear Mount Intermediate ring is removed, both parts of the helicoid will turn independently.
The idea here is to turn the front just enough so that the front cover screws will be exposed.
Disassembly of the helicoid is not necessary.
Mark all parts so that you can put them back together easily without guesswork.
Upon reassembly turn back just enough to align the screws mounting the intermediate body ring.