Getting ready for our trip to Colorado, changed fuel filters, checked oil and tranny fluids by the Prevost book. noticed a lot of grease around shield for radiator fan belt pully, cleaned it up and shot some more grease into fitting and also the belt cylinder but noticed that the main "big" belt for the radiator looked a little "loose" while running engine to leak check fuel filters. I can actuall grab the gearbox assy at the pulley (of course after shutting off eng/batteries) and give it a pull/shake and the whole assy jiggles. Is this right? I don't remember doing it before. I did not have the engine running long enough to really build up any heat. With the engine running should not the belts be turning a nice smooth rythm?