Dan,
The condensers are facing each other, both curved edges towards each and flat sides facing bulb and negative carriers. There is a third condenser that you move to adjust for the lens size, ie 50, 80, and so on.
I did some more investigating and there seems to be a bright spot near the top of the frosted part of the bulb, facing the negative stage when it's lit. Although very small, 1-2 mm in diameter when looking at the bulb, it's very noticable. I'm thinking that the condensers are magnifying this imperfection in the frosting and therefore showing up as a bright or hot spot on the prints.
Do you think I could put a thin piece of diffusing material, like a Rosco gel and that would help soften and blend the light evenly? (Or just buy a new bulb, seeing as this one is probably 20 years old or older).