I use a Wallner System 500 Modular system in my darkroom. It was purchased impulsively a few years ago and has served me quite well. I have found little information or support sources on this gear and have started a Google group as a place to accumulate information and share experiences. The group is at:

http://groups.google.com/group/wallner?hl=en

I've uploaded the material that I have as a start. It's a public group and perhaps over time, people will find it and add to the information. I'm using the System 500 Labex/Wallner...picture attached.

Wallner's business was taken over in 1988 by FEM Kunze, and they still make darkroom meters. You may be able to obtain information from them.

http://www.fem-kunze.com/