I have a 2003 Monaco Exec 40 ft. The Aqua hot was not warming the living area or the bathroom, the bedroom was toasty warm. Took it in and they found one leaking pump out of 3 pumps. They replaced it ...
There are check valves above the pumps that are know to stick closed. Tapping on them with the wooden handle of a hammer should unseat them. Anyone who works on AH should know this.