On my last rig the valves were a nice straight shot from curb up to the tank. More inconvenient to reach down under the rig to pull...but opened with barely any force. Our current rig has a "wet bay" with all valves, plumbing, shower etc in a nylon compartment. Valves are quite stiff even after being replaced under warranty. Apparently the cables take a turn going from wet bay down to tanks. Much like the brake cable on a bicycle...the more twists and turns, the more friction in the cable. Im not sure you can do much except seek the straightest run possible in the cable. Hopefully you find a solution.
Daryll
