What could this be Tube Failure

From the Upscale Audio Technical Help section:

Some of my power tubes have this eerie blue glow on the glass. Is that normal?
Yes, that is normal for power tubes. That blue glow is just stray electrons bouncing off the glass. Some tubes will have a more noticeable glow than others, even amongst a matched set of tubes. Sometimes the glow will burn off, that is normal too.

What is NOT normal is a bright blue or purple glow coming from inside the plate structure of the power tube. If you see a bright blue or purple glow coming from inside the plates, turn your amp off immediately and replace the tube.

Regards, Rich

i'm afraid this is the latter
I have powered down the system and waiting to get a tech to look at it

I don't want to change the tubes and find out something else has happened and add to the issue

Anybody else care to offer their opinon on what's happening ?

Pull out the tubes and ask someone to test those tube...Hopefully some of your audiophile friends own a tube tester.....that is your number one thing to do...then if those tubes are strong enough and no leak...let some one check your amp.