as your sight line gradually moves back toward the optical axis, does the primary edge still remain visible when the edge of the foam lines up with the edge of the primary baffle opening?
I believe it does, on closer inspection the full primary can be seen from the visual back with room to spare. And from the diagonal, the primary's edge appears to very closely coincide with the primary baffle opening (image below.) The secondary baffle 'base' (the foam ring) lies just outside the primary's upper opening and the primary's edge just inside. And I do mean, "just." LOL
Okay, it looks as though the primary's edge does J U S T fit inside the primary baffle at the diagonal back focus. The edge can be best seen about 8 o'clock. The 'fuzz' is the flocking paper. It seems consistent with the star test, too, as I can see that "intrusion" near 11 o'clock position.
Man, that was difficult to discern. A game of millimeters, or fractions of them...
But, apparently the primary's edge and the foam baffle ring are very close together with the primary's edge just inside it. So much so, I thought the foam ring obscured the primary's edge...all this time. But, such a design makes sense allowing the secondary to catch off axis light.
So, at diagonal back focus, there is so little room for flocking the end of the baffle. I might just have to live with it or risk reduced aperture.
And the tight fit is consistent with a very small unvignetted TFOV...that I want to observe again during collimation. I never noticed anything in the 11' arc FOV at high power, previously. However, vignetting became apparent nearer to the edge of 20' arc FOV. So, I suspect the FOV is admittedly small, unvignetted, and just fine for planetary observing (apparently what it's designed for, or advertised as such. Acclaimed to do, maybe, lunar and planetary.)
So, in the end, the secondary baffle seems almost useless except for low power viewing directly in the visual back (which I rarely do...never done, in fact.) Some efficient flocking darkened up the mechanical innards to prevent off axis reflections back at the diagonal. I might just make the flocking permanent and be done with it...leave the secondary baffle off and run with a 30.7% co and full aperture.