That's great progress and it's wonderful that they are taking on this project!
I'm embarrassed to say that I forgot about this leak testing technique even though I own a specialized HV probe used by glass blowers to search for leaks.
However, if the leak is at the ultor flange as Bob and John think, then I doubt that this technique will work because the metal is an equipotential surface. You wouldn't be able to pinpoint the leak. Also, since the flange penetrates the glass it would conduct even better than a pin hole in the glass.
Unless I'm overlooking something.
John