We picked up this coach in late February 2021 and have spent long hours getting familiar with systems, changing fluids, belts, filters. Lately I had searched my owners manual for the location of my pump and reservoir location. Manual stated it was in the drivers side compartment just behind the rear tire. Well no compartment there, my side radiator occupies that space.
I researched all the forums, downloaded information on Monaco coaches 2004-2006 with similar equipment. I was able to locate the pump and reservoir in the generator bay buried between the headlights and the step motor mechanism. I added dextrin III per instructions in owners manual, 1/2 quart. This solved my issue of bong alarm activating on rough roads and sharp turns.
I hope this information helps someone with similar issues.