I'm new to living full time in a 5th wheel (city hookups) I bought an Alfa Ideal 2003 and my galley tank says full I know the sensors can be wonky and incorrect but I genuinely believe the tank is full however I can't find the valve for the galley tank my sink doesn't drain and it smells absolutely nauseating under the sink. I've changed the vent under the sink but it hasn't helped, i can't take the p trap off because the smell makes me vomit. the sink backs up and leaks. I have 3 valves outside a black tank and I'm assuming grey tank and galley but my gut tells me there's another tank hiding somewhere near the kitchen but where? I can't find ANY info about alfa 5th wheels since the company is no longer around. Is there anyone in the Sacramento California area that can help me?