I had my selector valve get stuck. Truck came to a complete stop on the highway while pulling a trailer in a construction zone with no shoulders and concrete barriers on both sides of the two lanes. That was nerve wracking, trying to get it to start, hoping the valves would get unstuck, all while not getting hit. It did get unstuck, got it started (love my interstate batteries), and made it home on that one tank.
When I took the selector valve apart, it looked fine. Cleaned it up while apart, put it back together, and it stuck again a few weeks later. Installed manual selector valves like the ones posted in here, and it has been great since.