Thanks vinylzone and millercarbon, on rca vt231 you can see where key may have been on the other tube not so much. If my memory is right I think my Mullard fx2's have numbers but none of the 6sn7's are numbered. I even pulled out some matching tubes but there is no consistency in orientation of keys and plates. I may have to junk the Sylvania black glass if there is no way else to tell. Any other ideas, thanks for trying.
Broke key guide on 6sn7 how to keep using tube
I broke off the key guide on a black glass Sylvania vt-231 and a black glass RCA while using a Garage 1217 tube adapter. The key hole is very tight on these adapters and so are the pin sockets. I know the tube is still good just don't know how to orient the pins withe correct socket holes. If I can figure this out I can just use a paint pen on tube and socket for the future. There are no numbers in the bottom of the tubes so where do I go from here? I have more of these tubes but hate to throw in a junk drawer. Thanks for any help.