Are you sure it is leaking? When I first got mine, I had the same thought. It was just residual water in the drain piping that found its' way to the discharge cap on the ride home. Using something like this is where I'd start.
https://www.campingworld.com/twist-o...lve-27868.html
then a clear elbow like this could help you determine how big the problem is.
https://www.campingworld.com/3quot%3...ter-16835.html