7 way trailer plug issue...

Thanks for the replies to this point, and no, I've never heard of the issue (not working below 10 mph....seems strange to me). But, I also know at basically 'any' speed, it doesn't seem to work in my case. Haven't heard of this 'device' that can be plugged into the 7 way socket either....seems I have lots to learn. Not sure how easy/difficult it is to open up the socket, but that looks like my next thing to check? Either that, or pay someone that knows what they are doing to do so.

Thanks...