My coach came with electric dump valves. First trip out from the dealer, black valve would not close all the way. Dealer replaced valve. Next year, grey valve wouldn't close, so I panicked and ordered new valve drop shipped to us in BC Canada. Paid $85 import duty to pick it up. 1 hour at campground to swap out. Next year it was the black valve's turn again, but I made a discovery, loosen the mounting bolts a half turn and valve works more freely. Worst part of swapping the valves in my coach is that they are buried behind the wet bay panel, and behind the flex hoses to the manibloc panel. So this last winter, I cut the wet bay panel into 3 sections, so access is now fairly easy. I also installed new style electric valves from the same vendor (supposed to be way better). This summer, I got some TP stuck in the black valve and it again would not close all the way. Made a mess at the dump station, but I cleared the clog somewhat so we could get on the road (after cleaning up the mess!). At home, I pulled the valve and found the culprit. TP the size of a cigarette butt stuck in the valve. So always use the black tank rinse after dumping! I met another Beaver owner who, like you, has a coach modified with manual valves on curb side. To keep things simple, if I were you, would be to get rid of the cross-coach piping and install cable-operated manual or electric valves in the original, street-side location. And the new style electric valve do seem to work better, despite my tribulation. Its always something!