It works fine. Notice what looks like to be a discoloring mark resulting from heat. I wonder what caused that. I was thinking the PC didn't work because of that but turns out it does!
If it's from 1993 it wouldn't look like this one. It would be like this, with the softer plastic. The one above used the older style brittle plastic cover with a window that's glued on from the outside (which is why the 1980s Fisher Pierce photocells tend to loose their windows if the window is faced into direct sunlight).