Regardless of how you resolve the issue with the check valve in your pump, use a pump screen to prevent future debris from getting into the pump.
https://www.amazon.com/rv-water-pump...+pump+strainer
We had a similar problem several years ago, and did not have an RV dealer nearby. I went to a local hardware store, picked up a 1/2" check valve that would fit the PEX, and cut the valve into the PEX line on the pressure side of the pump, which fixed the problem. Even with a new pump a couple years later, just left the valve in place and still works great. I would not recommend installing the check valve on the tank side of the pump, because the fittings on the water pump screen/strainers usually can not handle the pressure. Installing the check valve might just save you a hassle at a dealer and a lot of down time for a simple fix.