It was time to check, and in this case, just change the impeller. There looked to be nothing wrong with the current impeller but we decided to just change it anyway. The cover was a bit dirty and had some salt water calcification built up so we sanded it a bit with wet/dry #400 sand paper. Then used some Scotch Brite on it.
Oiled up the inside of the pump and impeller and the cover along with the new O ring and put it all back together.