[mikethedruid]

Which socket are you trying to replace? Is it the one for the 50L6? That would be an octal socket. The rest are all locktal sockets, which the one you linked to appears to be. Locktal sockets are harder to insert the tubes into than octal sockets. They are supposed to be. They were developed so that tubes would not come loose from vibration in military applications. You just have to gently wiggle the tube from the base to remove them, and the same to insert them.