After reading several macerator premature failure threads it seems that many macerator are installed where they stay filled with holding tank waste in between use and the pressure of the tank water against the seals constantly. The factory installation in our boat has the macerator level with the bottom of the holding tank and below the waterline with instructions to open the seacock and start the macerator pump and turn off the macerator as soon as the tank is empty then close the seacock. So in between uses the macerator has seawater in the discharge line and black water in the intake side...a tough life, especially if infrequently used. More frequent use and maintenance may be part of the answer, bit a better installation to help the pump succeed seems to be needed.
We've owned our 2008 h36 for two months and the macerator is shot. Motor won't run (open circuit) and very hard to turn using the motor end shaft slot that made for a screwdriver. It did not show signs of leaking. Note this is a Jabsco self priming macerator 18590-2592.
Based on my interpretation of Peggy's and others comments, I'm proposing to install the new macerator above the waterline to keep salt water out of the discharge and place a loop on the input to keep black water out of the pump in between uses. Comments or improvements appreciated.
Dan