The Duplex that I sourced for $50 just arrived. I plugged it in and it works, and the doors move up and down fine. The filters don't appear to be in the best shape, and it looks as if they were taken apart at one time and probably replaced with something else.
The hum of the thing isn't so bad. It's a steady, low level hum, and reminds me of something you'd hear from a fridge or chest freezer when the compressor is running.
I'll be looking into replacing the filters, so if anyone has tips if appreciate them. I seem to remember Rosco "Fire" for the red ones, but what about the yellow.
Here's a few pics:
There's just a little bit of damage here . The left seam doesn't lay flat.
And here are the filters. The red ones seem to have a green layer on the outside, I would assume someone put there to block some of the light.
And the iPhone camera does funny things in this light. The wavelength is really visible.