Yep its the NRV thats failed and depending on your fitting as to location but usually with Jayco if you have the dinky white hose fitting which you plug your hose onto, the NRV is located inside that, the easiest and most simple way to fix it is buy a John Guest NRV fitting which you fit to the line just inside from the hose connection, a clean sharp cut of the poly pipe and taking note of the arrow on the fitting plug it in, this fitting will cost maybe $20 to $25, not all PRV valves have a NRV so I would go the Guest fitting myself, as a PRV will cost you $60, always handy to carry a few guest fittings in the spares box....
You can pull off the hose fitting and use a side cutter to cut the dodgy valve out so it doesn't slow the flow.