Generator won't start...When we were at the dock, we started genny prior to going out on the water & it started & ran fine...Once out on the hook later that night, genny wouldn't start..We get a sort of humming noise when pressing switch..We have tried to start from the switch on the unit with same result..We have replaced the battery..Oil, coolant & water are fine..We replaced the impeller last year as it started but switched off after 10 mins or so...Over heating is not the problem this year...It just won't even start...I have read a lot of your posts..Circuit boards, solenoids, breaker, fuses ??..Thoughts ??