I have a pair of Haltron EL-34 tubes. I've had them for a long time and can't even remember where I got them. I had not looked at them in some time and looking a them now, something seems strange about one of them. It appears as if there is no silver coating inside the top of the tube. Just a bit of white. Here's a picture of the two tubes: Before I go ahead and plug these in to my amp, can anyone tell me if the one on the left is damaged or faulty in any way? Or is the lack of the silver coating not something I should be concerned about? Also, I've read that Haltron would rebrand tubes made by other manufacturers. Can anyone tell if this is the case with these tubes? Here's a picture of the bottom if that helps. I read that the hole in the guide pin could indicate that they are from the early 60s. MaybeTeslas? Thanks for any information you can provide.