Hi Don,welcome to the forum.I have a 77 argosy.I went through the same thing you are going through. you will get some good directions here.I did.the power unit will hum.check to see if the ac power cord is hooked up while the generator is running.Is the gen on the right side and the ac power on the left side?The ac cord should be unpluged whie the gen is running.If it is like mine the ac power cord unplugs and there is another plug that you plug in to it's place.. also replace all belts and hoses and thermostat and antifreeze..
Bob