I keep filling my fresh water tank every week even though I use very little fresh water. Obviously there’s a leak somewhere. The pump was recently replaced by the former owner and it does look new from what I can see. When I use water, there is always air in the system and it spits out the faucet. I’ve looked inside the tank with a camera and the tank appears to be sound. Does anyone have the fresh water system diagram for a 3807 or the likes. Are there valves to shut off the aft and forward heads (sink and showers)? Did anyone experience this? Also, seems difficult to access the pump to tighten all hoses/fittings. Any suggestions. Appreciated, Ray