Beautiful cameras. I have seven of various Werra models in my collection - each of which I have either rebuilt or restored. Are you sure that the selenium cell is dead? Whatever you do - don't disconnect the lead from the selenium-paint face of the cell - because you won't be able to remake the joint unless with electrically conductive epoxy (hen's teeth stuff). But isolate the other ends of the two wires and see if the cell yields any (very low order) voltage under strong light.
If it does - you can boost its reading by removing or shorting out the ballast resistor. I have done this on a couple and arrived at readings which were within one Stop accuracy - which is of course easily compensated as long as you are aware of the under-reading.
When I need conductive epoxy I go to an auto parts store and buy one of the small kits used to repair rear window defrosters. A small tube of epoxy is included.I don't know how it stacks up against other sources but I have used it to attach a new wire in my Elecro 35 GSN in place of the original which had coroded.
