Fresh water tank drips that slow overnight are usually near the tank top - check fill hose, vent, and overflow connections. Inspect accessible areas before dropping the underbelly.
Yes, you can safely add a manual ball valve to your '08 Fleetwood Terra's heater line before the electric valve. This will function identically to the electric valve and won't cause flow issues since the system is designed to handle closed valve conditions.
Thor Ace has both macerator and gravity dump. Look for valves in the wet bay that direct flow to one or the other. Close the valve to the outlet you are not using. Some setups have both connected - gravity works by default, macerator works when pump is on.
Everything you need to know about RV plumbing systems from fresh water supply to waste management.
Montana 3793RD black tank valve is at tank outlet near dump connection. Access through underbelly panels. On 2023 unit, likely warranty covered - contact dealer before extensive DIY repair.