I have a Dig 220, Autopilot rc 42 and am seeing the "check clean cell" message. I live in the Midwest and only use the pool 4 months a year. The generator is 5 years old. Salt level is 3200 ppm, 2.8v, 3.6 amp after boost test. Is it likely a bad cell? What should I do next? My chlorine levels so...