I used this plug in your 4119 panel mount socket and discovered that it damaged the spring inside the socket, stopping the socket from gripping the plug, resulting in a bad connection. I know that the problem wasn't with the socket, as I used it with your USB - 2.1mm lead and it worked well. The problem seems to be that the black plastic ring at the end of the plug isn't of consistent diameter, and can damage the socket. The solution I came up with was to file a little bit off the black plastic, reducing its diameter. That seems to work, but isn't a great solution. Has anyone else reported the same problem? Could you source a higher quality plug?
This is the very first complaint I've had with any of your products, and I'm otherwise very impressed.