This one was kinda dangerous in an exploding propane kinda way.
I don't have a good picture here, but the propane hoses that came with the trailer were kinda strange. The blue-green, what is that color?, teal? knobs that you tighten to attach the hoses to the valves on the tanks have to swivel. That's a given. But that is about as much as is needed. In addition to that swivel joint there was a second joint on that end of the hose. Why? On the other end the nipple that attached to the regulator swiveled, and then there was another hex shaped section and a second swivel joint. That's a lot of joints...to leak.
The first camping trip everything was fine. The second trip I opened the tank valve, went in and fired up the refrigerator, and then was behind the trailer and smelled gas. Sure enough more than one of those joints were hissing away. They weren't doing that when I started things up. Had I zipped up the nylon cover for the tanks after opening the tank valve I would have had a balloon full of propane on the front of the trailer.
I tried to patch things up a bit with Super Glue and electrical tape. It's all I had with me. I didn't trust it, but tested it later and it would have worked had I needed it. During the trip I just turned everything off and left everything in the ice chest.
I replaced the hoses with Mr. Heater hoses I bought at Camping World that have only one swivel joint right were you would expect it to be. By the big knob. You just have to hook up the end to the regulator first, since the hose will spin when you tighten it. I used a little Rector Seal on those threads.
When I was hooking things up I noticed that the tank selector lever doesn't really seem to do much. With only one hose hooked up to the regulator the gas would come out of the other hole no matter where the lever was. Huh. Anyway, it's all better now.