This may be of some value:
http://www.robertsuomala.com/5.html
Are you sure the bulb is not in there? If it is not there you will see a hole where the bulb would go. You could aim a bright flashlight in there. If the ammeter needle moves, even just a little, you will know the unit is complete.
I've got two of them, one almost working but with original parts and the needle barely moves. The other had corrosion that made the filters golden brown and so that one I tinkered with. I almost got a modern solar cell to work as a replacement for the selenium cell. But even that modification was too fiddly.
I bought a dozen 1.2 volt bulbs with round heads that are close to the right bulb for the job. I used sandpaper to frost the bulb.
When I use them, I tend to calibrate bulb brightness not to the internal meter, but to one of my other meters.
If the part is missing, it is "just" a disc of brass turned with a ridge and notched to fit over a pin. There is a nut that holds the bulb, though some versions solder the bulb in place.
Bill - thanks for questioning whether the bulb was there. It made me take a closer look. There was no hole where the bulb should go because the bulb was there the whole time! I feel like an idiot. The unit has the sleeve and the complete bulb assembly. I put a D cell battery in and pushed the little black button on the end where the battery inserts and the needle swung way over! I think this unit is complete and operational after all. Thanks again to everyone who contributed to this conversation. As I said, I'm gaining an education for sure. Now to find a buyer! God bless! Mark
There is a classic video of Ansel Adams using such a device: https://www.youtube.com/watch?v=DQT_rzI1Xdw
That was very interesting - thanks for sharing! Mark
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