Following your instructions, I removed the escapement mechanism, disassembled it, cleaned it with acetone and oiled the bearings. The new shutter speeds are now very good in my opinion.
I'll clean the viewfinder tomorrow. And then I'm waiting for the spare part Atoron, which I bought today for 20 euros. It reportedly has a working light meter (although it is in poor external condition).
Current status: The spare part Atoron arrived yesterday. At the end of the week I will try, following your instructions, to remove the selenium cell and install it in my Atoron.
I unsoldered the black (negative) lead from the existing cell and soldered it to the marked (-) terminal of the new cell. The other end of the cell is marked (+) on the back.
Since the new cell is too thick to fit in the old mount, the old mount will not be used and the cell will just press up against the screws shown when the case is re-affixed to the front of the camera.
I thought I might have to add a bleed resistor or mask part of the cell, but it works nearly perfect against the standard light source. Nothing else needs to be done.
I unsoldered the black (negative) lead from the existing cell and soldered it to the marked (-) terminal of the new cell. The other end of the cell is marked (+) on the back.
Since the new cell is too thick to fit in the old mount, the old mount will not be used and the cell will just press up against the screws shown when the case is re-affixed to the front of the camera. View attachment 383806
That's pretty slick! Beats what I've been doing, which is cutting crystalline PV cells by hand, but they are oh so fragile. IME, there's no need to closely match the size or shape of the original selenium cell, because while silicon PV produces similar voltage as the original part, amperage is ~10x as high.