The part # 71-5002 wasn't known, there have been units found with a 5000 and 5001. The other interesting part is that it has a different front logo than the standard model. Here is a site with more information:

http://coco.8bit-micro.com/videotex.htm

Since the Videotex Terminal is based on the CoCo, maybe should be added to the database?

Corey
8-Bit Classics