Okay, I realize this is almost so simplistic as to be ridiculous, but here it is. I have a C machine, and I purchased a new probe from the conference. When I go to plug it into the top left side outlet, using the extension, it just won't plug. I read that the small plastic release may be top or bottom. I've tried both. It just doesn't make a secure enough attachment for the machine to recognize the probe is attached. Additionally, it just doesn't 'look right', if you know what I mean. Any thoughts and any suggestions appreciated? Thank you.