I used a dab of Vaseline on mine. Shouldn't have used that on the rubber o-rings, but that's all I had at the time, and it worked. Eventually I'll have to replace the o-rings, but perhaps by then, I'll just put 1/4 turn ball valves in there instead.
I would use the aforementioned plumber's grease or keg lube on those o-rings. That should get you fixed right up.
2014 Jay Flight 28 BHBE
2015 RAM 2500 6.4L HEMI, Tradesman 4x4, 3.73
Blue Ox SwayPro (BXW 1503)
Upgraded from an REI internal frame backpack and a Eureka 1/2 dome tent!