I have the same set-up as you. The black and one gray tank valves are very easy. The second gray valve, feels like I'm going to pull the handle off. Been that way since day 1 also.
Keith & Drena with Casey & P-nut (dogs) & Gabby (cat)
2014 Silverado 3500HD Dually 4X4
2014 Evergreen Bay Hill 365rl