Maybe simply changing the tube brand would make the head more reliable so.
Damn...and the Tung Sol are super expensive too, which with the recommendation of the tech made me think that would the mark of some "high level craftsmanship" you know...
What tubes brand/model would you recommend so, gentlemen ?
I think it was Nick at Dunwhich that said, you will see a much larger difference in tube type, than tube brand. They are only coming from a small number of factories anyways. Go with something easily available, so if you have to replace a single tube, it will be easy to find one that fits with your set.