We lost the FW pump on the Westerbeke that was on our boat when we bought it, at about 3,000 hours. Nothing dramatic about the event--we were a day into a week's summer cruise--but the pump just desintegrated. We had great service from Portland Yacht Services' Parts Dept, who got a new pump to us w/in 24 hours. It was a simple installation that took me a couple of hours. But the real lesson is that we would have been really stuck without the immediate delivery of the replacement part. It is/was unique to the specific make and model of the engine. So I you plan to be self-sufficient and need the engine for propulsion, charging etc., then you should carry the spare.