Thanks for the description of the transformer.
Tey use the transformer dial to adjust the voltage, which will reduce the output to the lamp. That can be used to lengthen the printing time, except that the different output levels will have different filtration requirements due to the red shift that occurs when dimming the lamp.
Anyone have one of these transfrormers laying around in need of a good home? I'll put one together for my own purposes if one doesn't show up anytime soon.
The one enlarger also came with an interesting multicontrast filter kit for the head. It has 8 metal sleeves in tracks that work similar to waterhouse stops, but each one has a particular grade of multicontrast filter. The filters are old an need to be replaced, and only having 8 filter choices is not ideal, but it may be a useful device. I'm going to work with it a little and see if it makes sense to use it for printing. I often use split filter printing, and this would make that approach easy to do, as the change from one grade to another would be very simple. That product also appears to be made in the US by Durst USA.