Agree with just running completely new wire. 12g or 14g should be fine, but do use bigger wire than the factory did, it might matter, it might not, but wont hurt. I used speaker wire from HD.
When I redid my last trailer I also made all the wire connections inside a storage box and not outside under the trailer, this keeps the wires and open ends dry and safe.
The magnets do go bad sometimes, and will eventually fail after many years. For just a one year old trailer maybe not start there, but old trailers it is just easier to replace all the magnets while you are messing with it all. They will fail. etrailer.com has all your solutions, and you can email them for pro answers too, there is a "chat" box on their site.