[Joeztech]

I agree with Morzh. Octal tubes fit firmly enough in their sockets, but the loctal types are real bears sometimes to remove depending on available space nearby for finger access and maneuvering. When I first encountered the 7xn tube types many years ago I first expected them to have a 7 volt filament until I looked one up in a tube manual and saw that they used 6.3VAC or DC just like many other tubes. Making a sketch of connections to a tube socket before disconnecting anything can be a big help. Alternatively, if you can take a good resolution well focused picture of the area with a digital camera that will suffice too. Be sure to note the orientation of the key-way or indexing key of the tube socket. I find octal tubes much easier to count the pins from the key than loctal types. Loctal sockets are very difficult to determine the position of the key from under the chassis by comparison to octal types.

Joe