Hi Eckhard,
The main difference between the successful (so far) rebuild by RACS was the use of frit glass to seal the junction between the glass and metal at the front of the tube. The rest of the rebuild was normal. So far the tube doesn't leak, and displays a nice picture. We will watch it for the next few months to see if it continues to work.
Here is a page with pictures of the original tube, the rebuilt tube, the frit glass seal, and the tube in operation:
http://www.earlytelevision.org/2010_...tion_RACS.html
Jerome Halphen is taking two of his 15Gs to RACS to be rebuilt. If they work, RACS will be ready to accept tubes for rebuilding. They have promised to provide a price for this soon.