Western Electric 300B problem

Blue glow = good thing, in fact sign of a good vacuum of a power tube. I have several NOS 6L6 and 6550 that have a beautiful blue glow. However, never seen blue glow with any of my new production 300b, Gold Lion, LinLai, Shuguang, or KR Audio.

Vacuum loss very apparent if gettering turns white and flakey. Otherwise doesn’t sound like a vacuum loss. I’d expect Upscale Audio will take care of you given their reputation. Have you emailed WE? Maybe a common burn in symptom? Although burning smell not good! 

Best of luck, let us know how it turns out.

Transparent blue glow that's generally found at top of tubes is something I often see. This was a sudden flash of extremely opaque or fog like blue that enveloped entire tube, this accompanied by a loud pop through loudspeakers, I wasn't going to wait for further events, amp immediately shut down! This happened perhaps five minutes after firing up both monoblocks, had just taken pre out of mute, very low volume level, didn't hear any noticeable distortion, music playing right up to point of blue flash and pop.

Forgot to mention. No white, flaking on getter, I too have seen this with some 101D tube failures. The other thing which I've failed to mention is mechanical noise from failed tube when first picked up, not that this is completely unknown previously, just noted from the beginning,

In regards Upscale, just received my Return Authorization. I explained symptoms and sent photo, they agree tube defective.

Good news! I hope this completely solves the problem.