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.
Back to Grenada in early December. Not sure I will remember how to sail. Will spend the winter and early spring in the Caribbean and then head to Bermuda and the northeast US. Still trying to decide if we will bring the boat to Canada, either in 2015 or 2016.