Contaflex Super BC loose optical mount

This is --partly-- a follow-up to an oldish thread about double images:

Returning to that camera, I noticed that, grabbing the front element, I could move it very slightly, the tactile input confirmed by the sound.
I embarked into an overhaul of the camera body; the Super BC is more over-engineered than the contaflex I or II. After dis- and re-assembling the lens assembly to the front plate, and the front plate to the camera body, the wobble of the front element had disappeared. Joy! A few test frames... double images still here.

Then, having removed the front element (bayonet mount) I now grabbed the center element, and... it wobbles. Very little, but it wobbles. And the slack is somewhere between that element and the base of the shutter assembly (that interfaces with the front shutter plate). Pretty little documentation about the shutter assembly. The Zeiss service manual considers it as a single component. The Deckel manual just gives a (partially) exploded view and some cutaways in the lubrication section. So I unscrewed the middle element, then removed the light baffle plate, the speed cam and main ring. See below



The screws securing the brass barrel A to the black baseplate B are tight. But the baseplae B jiggles slightly with respect to the aluminum casing C. I an reluctant to dis-assemble the shutter components: will lose speed adjustent which sounds OK for now.
Question: where are the screws that fasten B to C ?
Thank you for reading

For the convenience of viewers, and to avoid going back to that old thread, the problem can be summarized in this 2017 image of a 220V tungsten lamp powered at 120V, and photographed at ~3m distance.