Thanks for the info - just the kind of detail that will save people a lot of hassle and money. I have a W58 but have just changed the pump and have an extra on in reserve (probably the same one you have).
Westerbeke parts are criminally priced. I had to buy a two-groove pulley for the alternator belts and it was more than $500. The single-pulley one was $80.
Heading back to Lake Ontario for this summer. Relatively few stops along the way from Grenada. Martinique, Guadeloupe, St. Martin (must have something to do with the French food), then Bermuda, New England and up the Hudson/Erie Canal. We were going to go via Newfoundland and Labrador but June remembered that one of the kids is getting married this summer - details, details!