slow drip from low point drain on a Roadtrek

[treker]

This is probably a silly question for most of you but here goes. I just finished going over my 2006 Roadtrek to get it ready for travel. I filled the fresh water tanks about half full and tested the taps for leaks ect. I noticed that the low point drain outside is dripping. I turned it on and off a few times to make sure nothing was caught and this might clear it but it is still dripping. Is there anyway to tighten this or is it like a hose with a washer? It is made of brass and it looks like it comes off as I think I can see some of that tape they wrap fittings with. I don't see all that well. It has an up and down valve that turns it on and off so it must be not closing tightly. I hope this is something I can fix myself. I did leave this valve open for winter as I was sure the Roadtrek instructions for winterizing said to. I would appreciate any suggestions before I add this to my list of things I can't do. Thank you