I had a similar incident with my Landmark, the doorside LP tank would not turn the indicator green. I replaced the regulator, same problem. After a little testing, I then replaced the Pigtail from the tank to the small regulator on the doorside and all was good. ( As good as it can get with the small hoses and the small regulator you get from the factory, even after the new pigtail the regulator indicator would drop down when the generator was running). I then noticed when I was running my LP generator from the off door side tank the indicator was fluttering between red and green, I replaced the pigtail on that side, made it better. I was told that that the check valve in the pigtails can go bad.. Especially if there is moisture in the tank.