I had three Galley Maid heads in my Chris Craft Constellation - two are now gone and the third is dead. They work well for about a year or so in live aboard service, then need rebuilding (bearings tighten up and the rubber "impellers" harden). Complete rebuild kit is $200+, and in my case the pumps were located in god awful locations. Finally they use about 1.5 gallons per flush (quick fill of holding tank) and pull about 20A when operating. In short, there are many newer electric heads that flush with less amps and lots less water... I'd plan on replacing, not fixing when they fail.
Jim