NavList:

The rotating polarizing filter on my C+P seemed to work with my purchased filter when mounted on the sextant. Removed and hand held, the view changed but didn’t come close to blocking most light when the filters were crossed.

The polarizing assembly is just a rotating filter mounted on the nearest shade with three tiny screws. (Very tiny. I now have only two of the screws.) It’s a sandwich of two pieces of glass with, presumably, a filter film in the middle. Having all of that glass stacked up and rotating may be too much to ask without some distortion.

I’ve got three index shades. The 3rd (furthest away) has a very dark filter still mounted. The middle is empty and the first was missing one polarizing filter and now, without the rotating filter, is also empty.

The best news is that I ordered a 43mm red camera filter. The glass was held by a screw ring that I removed and the glass measures 40mm- and fits the shades exactly.
I think I’ll order another, blue, 43mm filter and have two possible contrasting images or a dark image if I stack them up. From John’s experience, it doesn’t sound like it’s going to be easy to order minor bits from C+P.
I’ll try to test the accuracy with the new filters in and out when I get it assembled.
Regards, Noell