Okay, your problem was intriguing enough that I took some of mine and tried them in every banana jack I could find. In only one case -- one of those in-wall connectors -- the Eichmann was too long for the hole and didn't make a good connection. In every other case there was no problem at all, and these ones of mine have been used to death and are still totally serviceable.
Are you SURE you assembled them properly. You slide the metal part through the black plastic, then slide the blue plastic on the shaft and lock it to the blue part with a twist. I just can't figure out why this doesn't work for you unless there is something very strange about your banana jacks. Doesn't make sense. Dave
Are you SURE you assembled them properly. You slide the metal part through the black plastic, then slide the blue plastic on the shaft and lock it to the blue part with a twist. I just can't figure out why this doesn't work for you unless there is something very strange about your banana jacks. Doesn't make sense. Dave