These are certainly rare! Shame they are dead.

Yeah what a shame theyre dead

In what way are they dead? Contaminated, full of air or just burned out?

Burned out. They worked brightly to the end but I always sensed that operation was a struggle for them, with signs of failure not being far off for most of their lives (premature end blackening and varying sounds of mains hum from the choke due to partial rectification).

That's a shame were they new when fitted or contaminated?

They were new unused when I began using them but obviously deteriorated while unused. What is the form of deterioration from the symptoms I describe?