7 Pin Trailer Plug

Posted this but think I did it on the old forum. I need to replace the 7 pin plug on my trailer, what’s the easiest way to do this? I need to go out and look at it more but is it an entire harness, how far back in the trailer does it connect to all the wires? I assume I can buy the replacement at most trailer shops as I’d like to get it done in the next day or two. It looks like I have one of metal pieces inside of the plug partially missing, been having trouble with the left turn signal. Do they come in a standard length, saw one online that was 6 feet? Thanks.